Asda do the pasta salads. I lived on them every day for 6 months while I was on my get fit regime. £1 a pot included either a prawn salad, chicken n bacon or a cheese one.
I used to vary them all so I didn't get bored.
edit: or I'd get a fresh salad 50p - £1 depending on size and buy the £2 chicken in packs. They did bbq chicken, plain chicken, tikka chicken etc