I have recently fallen in love with a brand called 'Look what we Found' who make long life meals in a pouch; chilli con carne, meatballs, chicken casterole etc. They are very similar to camping meals, they are tasty, can be boiled in the bag and will last for months, they are maybe not quite as calorie dense as made for purpose camping meals but they are a fraction of the price, I normally pair them with a packet of cheap precooked rice for a more substantial evening meal. I have seen them in several supermarkets, I pick mine up from Morrison's for just under £1.50 each, but if you google the brand name you will see they are pretty common and popular with outdoor enthusiasts.