So you want to feed 40 people a variety of meat based meals with sides and desserts and a homemade cake for little more than £1 a head? I don't think there's a hope in hell. And I''ll be blunt - unless you are a professional caterer with a full freezer and a shedload of store cupboard ingredients already to hand, and you can source the fresh stuff really cheaply at wholesale prices I'm not sure it's going to be very nice. Sorry.
How do you 'bulk out' pulled pork, meatballs, carbonara etc with veg? Chilli and curry maybe but not the other things. It's going to look like you couldn't afford the meat to make them properly and skimped on it.
What if you have loads of people feeling shortchanged because they've got some claggy congealed carbonara full of bits of random veg that shouldn't be in a carbonara when they wanted the chilli cone carne but there wasn't enough? How are you going to manage to cook decent hot chips and garlic bread, spaghetti, rice and homemade pizza all at the same time and keep them hot?
Apart from anything else, you have given yourself a ridiculous amount of work. The pizza, the carbonara, the chips and the garlic bread are going to need last minute cooking or the carbonara will go like glue and the pizza and chips won't be hot/fresh. By picking so many things that are cheap you are (imho) biting off more than you can chew work wise.
Simplify things. I would forget the pulled pork for a start - that won't go very far unless you stand over people and ration it. And the pasta dishes - they will be really hard to keep from going all congealed. I think you should focus on making fewer dishes, pick ones that can carry more veg without looking dodgy . I'd do something like this:
one medium heat chicken curry that will appeal to everyone (assuming they like curry at all)
one vegetable curry full of cheap and filling stuff like potatoes, carrots, peas, cauliflower etc,
And/or one lentil dal.
A huge pot of plain or pilau rice using a rice cooker
Perhaps some samosas or pakoras (can be made very cheaply in advance, fried off and then reheated in the oven.)
Some poppadums (buy the raw/dried ones very cheaply from Asian grocers, and fry them yourself in advance., not the expensive ready to eat ones.) A couple of dishes of chutneys and raitas.
Then for children and/or anyone who might hate curries, (I'd find out in advance so you don't buy and cook anything unnecessarily) I'd do baked potatoes and offer some simple toppings like tuna sweetcorn mayo, or cheese and beans.
Or:
Make in advance several quiches/pies with homemade pastry to keep the cost down. A couple of cheese and bacon ones, a salmon and broccoli one, a roasted mediterranean veg one, a couple of chicken and mushroom ones. Warm them through and do a range of simple salads using cheap ingredients; pasta salad, coleslaw, cold bean salad, boiled new potatoes in herb butter (frees up the oven to warm the quiches.) Maybe serve a tray of hot sausages for quiche dodgers and children.
Or a giant shepherd's pie and a giant vegetable lasagne and a big fish pie, all prepped well in advance and warmed through in the oven as needed, served with some frozen peas and baked beans. That might be doable on budget.
Ordo JUST chilli and rice with JUST a big lasagne and one simple type of salad and some garlic bread.
Or do the pulled pork for everyone, but to make sure you have enough to go around, portion it up and serve it already placed into floury baps with apple sauce, maybe do some sausages for the kids, some homemade coleslaw and a potato salad.
I think if you have even the tiniest hope of keeping to a small budget without compromising hugely on quality then you really need to simplify it MASSIVELY. And I quite often see pork shoulder joints reduced in Morrisons so you could keep looking and bunging them in the freezer until needed.
Likewise with the desserts. If you can buy cheap M&S cakes for a £1 a bag then perhaps just stick to those.
I still don't think you can do even the things I have suggested for less than about a hundred and fifty quid