Your IP should be able to provide the Stepchange guidelines although it is important to put down what you spend regardless of what Stepchange say. It is useful to know what you can claim for as some firms will not tell you just so that they can take more money from you and thus earn a higher fee.
(Sorry, have not yet been able to get hold of the latest version that came out in October 2013, but the figures only differ by a couple of quid here and there).
It is well worth a read, as it covers every form of expenditure, right the way down to allowances for hairdressing, kid's school dinners, meals at work, even hobbies etc.
My opinions are just that: Based on my experience and being a self-employed IVA customer.
It is useful to know - I included a lot of things this year that don't appear on the standard review form & they have all been allowed.
Pity I didn't know about this 5 years ago!