Very dry wit, very entertaining and amusing, but heavily flawed. This is one of the more funny (though not completely funny) and engagin first acts I've read (I only made it to page 24, at which point you lost me).
Your scenes and action blocks are generally pithy and well laid-out. Some of your dialogue exchanges are ripped right out of dry-Brit-humor 101 and had me smiling or chuckling. But there are a couple spots you missed out on a great payoff line (see below) and other spots where you completely struck out on entire scenes, but overall, the first act is pretty damn good. I'd be more inclined to read the rest if you were to punch up not only the first act but the entire SP. If I sound harsh, it's only because I think you have something here that could really sparkle. Right now it's still a bit dull and I'm trying to encourage you to polish it into the bright gem it potentially can be.
Your address on the title page is in the UK and that shows in your word choices in both dialogue and expostion. Not sure why you need to set this in US. You have the building blocks for a great Hugh Grant type of comedy, why on earth wouldn't you set it in UK? If you must set it in US, then you need to clear up a lot of the Britisms you use, esp in dialogue. One last overall crit... it is maddening to read dialogue where the characters are constantly referring to each other by name. If they know each other, they do not need to continually refer to each other by name--remove most of the occurences where they use each other's name to adress each other. It sounds unnatural.
My notes as I read:
Quick side note #1: you really have a thing for assimiliations, especially those including the letter H: Henry Howe, Horn's hardware, "we home in on Henry Howe's house,"
Quick side note #2: your first use of dialogue includes two characters with 3 lines each--and each time they speak, they address each other by name. Not very realistic. You can do away with all of their usages of each other's name if they are so familiar with each other, or just use one (we'll get that they know each other).
More importantly regarding that dialogue exchange between Henry and April on page 2, the only relevant thing I gained from it is that it seems Henry normally brings sandwiches and April's favprite cheese is Canadian cheddar. BFD! Unless cheese or sandwiches is relevant later on, this is absolutely useless. Either change it to something witty (this is a comedy, after all), or something more relvant to plot or character...maybe April knows Henry is getting "sacked" and it shows in her actions and remarks or maybe she's flirty or anything but sandwiches and cheese.
On page 3 in the accounts office, you have 3 straight lines of dialogue by Henry--the middle one is obviously misnamed. Also, you state that Henry is there with Lane, but Digby is the one who finally answers him. So are both Digby AND Lane in the room, or is simply a misnamed character?
Further down the page, Henry is asked to "collect" Ben from school. I realize you're from the UK by your title page, but if this story takes place in upstate NY I don't see anyone saying "collect the boy." They'd say "pick him up." Unless this is a relocated Brit family? But I didn't catch that. Same for page for when Angie says she'll "ring" him later. Rarely said by Americans. I'll "call" you, give you a "jingle," give you a "shout," etc.
One small suggestion: bottom of page 4 after Henry picks up Ben and the boy asks where mom went, you cut to them in the car and have Henry say "an aunt." Might play better and sound more amusing (and save you a line of space) if you instead start that dialogue block with Ben saying "An aunt?" We'll infer that the aunt is Henry's excuse. The rest of that dialogue exchange is pretty well executed as a stunned husband trying to lie to his kid about the abandonment of the mom. Shows emotion and bitterness, though you could play it out further for laughs or pity by having the boy ask more questions and Henry coming up with more frustrated, ridiculous answers to deceive his boy AND reveal more of his frustration and broken heart.
Page 5 cute line about Ben asking Henry if he was trying on mom's dresses--but I think you missed an opportunity there for Henry to start a funny dialogue on that subject. Ben's story about his friend's dad is cute, but this could be funnier still.
Page 6: Ben "tucks" into a pizza? Never heard of it reffered to that way. More Britisms? Also, later on when Cheryl approaches them at the pizza joint seems like everyone has to refer to each other by name. Drop most if not all the names.
page 7: Marcel (more of a French than Hispanic name, no?) and Angela sound more Brit than American in their dialogue. Okay, I'll stop mentioning that. Would it be such a bad thing to set this story in the UK instead of the US? Simply driving a pickup doesn't sell us on the "Americanism" of the story. If you don't nail the regionalisms of dialogue, you're sunk.
page 8: brilliant dialogue between Henry and Angela... but, toward the end Marcel cums after he jacks off and all Henry has to say is "Is that who I hear?" Please! That is the moment for your first, truly belly-aching laugh for the reader. Henry has to give a fall-off-my-seat-laughing line right there. It can go in SO many different directions depending on Henry's nature and emotional state: is he more pissed, sarcastic, mean, dim-witted, clueless, dumbstruck? You set this one up nicely now knock it down with a fucking bomb!
page 10: after informing Ben that he has some jobs to do around the house, Henry smashes his bed to bits... with an AX! Wonderful! Great, quick, little scene.
page 11: you totally lost me. Had no idea what Henry was doing at the dance center until you mentioned Marcel was teaching there... you totally set me up for a juicy encounter I was now anxiously awaiting. But you play it off like Marcel doesn't recognize Henry's name (and I'm sure he would after 4 years of banging Henry's wife), and Henry asks no questions about the relationship, shows no hatred, irony, sarcasm, makes no threats or lies ("Angela has Herpes.. but it's only type 4 so you should live, maybe" or "my uncle Momo is sending over a couple of his associates to pay you a visit... while you're a sleep.") This scene is such a let-down and not believable that I almost stopped reading.
page 13: pretty amusing dialogue exchange between Cheryl and Henry--good topic but I thought you underplayed it. I think you could've gotten more laughs (or at least chuckles) with Cheryl getting more descriptive, more detailed, more daring. Maybe her lover only gets hard if she offers him her ass or something that will shock Henry (and us) even more because before this she came off as pleasantly boring, but now she's a sex kitten. It's a good scene, but could be great.
page 14: GREAT scene with Henry and his wife. Wonderful dialogue and character reveal that she is a bondage freak.
pages 15-20: not that inspiring. Very oh-hum. I get what you're going for but it wasn't salacious or funny enough. You have a nice outlay with that scene but you don't really bring the laughs though I think you can (based on how you wrote earlier scenes).
Stopped reading at page 24. I see what you're going for, displaying Agela as a complete bitch by demanding money and such, but Henry is such a pushover, so docile. Does he have any backbone? Okay, if you want to play him as a docile, at least make him a funny or at least logical docile. If he's not going to be aggressive towards them, at least play the scene with more laughs, even though it's a dark moment for him.
That's it. Good start. Think it could be great. Don't rush back with a rewrite. Take your time, see what others have to say, then go about your rewrites methodically. If you come back in two days with a rewrite for reads, you haven't done your homework. Take a good month or more to let things settle in and work each scene till it shines. You really do have a good start to work with. Best of luck.