Hey
If you're looking to live on campus I would suggest going directly onto Lancaster University's website and checking the costs of accommodation there, but generally I would say the prices are pretty good and not too expensive in comparison to other unis, particularly in the south (which I've heard is renowned for being generally more expensive to live in). The only issue I have is that using the laundry services here can be expensive, but I think that's due to the company that owns the service (circuit) rather than the university itself.
If you're wanting to know about off campus accommodation, I'm pretty sure that for a standard house the prices are generally around £95 p/w but this obviously changes depending on what you want from your room. If you're interested in seeing what sort of houses/flats are available within the city for students Yellow Door Lets is a pretty popular company here.
In terms of food, the closest big supermarket to do a proper shop in (to the university) I'd say is Sainsbury's, which in itself is a little expensive. However, I personally do my shopping online at Tesco and get it delivered, which is a cheaper option. There are shops on campus too, such as spar and a co-op, if you need other things. There are also a lot of places to eat on campus that I would consider good value so if you want to eat out with friends there's always that option (and it's cheaper than having to go into town). I personally don't drink but I hear people comment that drinks are cheap in comparison to other places (and there seem to be countless offers for drinks in the clubs here).
Transport I'd say is pretty good value, I can get a return into the town centre (which is about 15 minutes away from the university) for £2.50 on the bus. If you're likely to use the bus frequently, there is also a unirider available.
Not sure where to put this final bit, but Lancaster University students can sign up to a purple card which can allow them to get discounts in certain stores. I wish I could remember how much the discount was, but I was able to use this in a Select clothing shop, so I'd think you'd be able to use it quite often.
I hope I've answered your question ok, if not feel free to clarify a bit further
Sorry for the paragraph, I got a bit carried away