You can put together some amazing salads for peanuts, buy the stuff from anywhere but Tansas! Depending how much food you want to take out with you in your luggage allowance, tuna and sweetcorn pasta is cheap and easy, you could take tins with you - cook your pasta, drain the tuna and the sweetcorn, combine it all together with some mayo, add salt, pepper, chilli flakes and paprika if you like a touch of spice. There are lots of simple pasta dishes you can throw together in a similar way that don't need to cost much.
I don't know how you are fixed before you go, and I wouldn't presume to suggest that any of these may work for you, but these are some of the things I personally do to increase the number of efes tokens I have available for my hols - anything I buy online, I make sure I check quidco first to see if they are one of their retailers, then you can get cashback of various amounts, (
http://www.quidco.com/user/465328/) - might as well get some money back for things I'm already buying. I have regular clear outs and get anything even half decent on ebay, you'd be surprised what people buy on there! Equally, I use ebay to buy things I need for the hols. I've financed totally more than 4 holidays in the last 2 years just from using these two methods.
In the weeks leading up to my holiday, I make a rule only to buy items on my shopping list that are on offer in the supermarket, I batch make pastas and casseroles and freeze them, then live out of my freezer for the few weeks before I go. No coffees on the way to work (which is easily over £20 a week!) packed lunches (saves at least another £30!) no going out (gives more time to do the holiday ironing!). I'm also a big user of coupons and vouchers - last year I had bogofs for the bar at manchester airport, it's amazing what you can find on the internet! The way I see it, any bargains you can find mean you can go on holiday more or have a bit more to spend when you are there. If you like a drink or 3 at the airport like we do, consider using a lounge, it often works out cheaper (but read reviews first to see what is included in the price) - quidco have a number of retailers you can book lounges through that give cashback too, so it's possible to have a 3 hour lounge visit for about £12.