Step 2 doesn't have to be expensive unless you have the meat protein options. Lentils and chickpeas are very cheap.
You can have about a tin of chickpeas per meal and that's 30/35p from the big supermarkets. A bag of lentils costs about £1 (again big supermarkets like Asda, Sainsburys) and you use half a pack to make the lentil soup from the booklet - that serves 4. Beans again are quite cheap if you get the ones you need to put in water....unfortunatly as you start getting the pre-soaked ones the price spikes.
Check Lidle regularly as they have offers on chicken style quorn pieces or mince for £1 every few months.
Sainsburys currently have chicken thigh fillets on offer for 2 packs for £5. I know we are meant to have breast not thigh but with 2 of us in the house on the diet and the quantity of chicken that means we have it's just too expensive to get breast meat. We opted for the thigh filets and just take the time to trim off as much fat as we possibly can. One pack is a meal for both of us for one evening (£2.50). You get 920g of thigh fillet meat for £5 which compared to the cost of breast meat is very good (usually £3.50 a pack)
Tofu - yuck...not going to say anything more on that one!
Eggs - lots you can do with them and depending if you go for free range, organic etc. you can still get half a dozen for a few quid and that's 3 meals right there.
What of the protien options do you like or not like?