£30 can be done. Don't worry! We live on about that for a week for two adults (although tend to not do a weekly shop) and can't imagina 2 year old can eat that much extra. That's assuming it is just food you need from that £30.
Firstly do you think your DP would eat quorn? I personally love it and think it tastes very similar to chicken. In a sauce I wouldn't notice at all. A 300g bag of quorn I would expect to get two meals out of minimum. Could also be used to bulk out a meal with chicken so you can use less chicken.
Another thing is look at large joints of meat in the supermarket. We got a huge joint of beef from Sainsburys last month which I chopped in to three smaller joints. I should have in fact cut it into four. We have eaten two so far and had lots left over from each joint which was good for lunch the following day. If had bought three seperate joints we were looking at £7/8 each where as the one big joint cost about £11.
For 7 evening meals I would suggest a combination of the following:
- Roast beef joint with veg
- Left over beef in a stir fry with noodles
- Pasta in a tomato sauce made with tinned tomatoes, another veg thrown in such as courgette or mushrooms and with quorn or a tin on tuna. Or use some quorn with a chicken breast
- A curry with quorn and chicken and some veg. Use tinned tomatoes as a base for the sauce as they are cheap
- Jacket potatoes with cheese and beans
- Another pasta dish - perhaps buy some creme fraiche or cream if your family will be bored of the tomato based sauce
- Par boil potatoes, chop into slices, place in a baking dish with layers of cheese in between. Also mix in chicken or quorn or tuna or something similar (I would cook first).
- Baked sweet potatoes with cheese topping
Would your DH eat leftovers for lunch? That way you can just make more pasta or more curry and he could reheat. Otherwise the leftover beef is also good for lunches. Also if you can get to Lidl's their cold meats are much cheaper than main supermarkets.
Turkey breasts are a good substitute for chicken as well although a little tougher.
Also if you usually buy premium brands then make sure you just buy the cheaper version for this week. There are some things like tinned tomatoes that I always buy the Sainsburys basic version as there just isn't any point in buying the expensive ones in my opinion.
Oh, I see you said you were going to Asda. They usually start reducing things at about 6ish. Head there then, find the area where the put the reduced stuff and see what you can get. you can quite often get very reduced chicken breasts which you can freeze and use a couple of days later. Also their indian and chinese ready meals from the counter end up in there quite a lot and at a cheap price.