There are many facets that make up the allowable expenses, but the basic 'Food, toiletries and cleaning' are around £100 (min) to £225 (max) for a single person, with a guideline amount around £170.
On top of this are the expenses for haircuts, telephone, medicines, clothing, petrol, etc. And then the 'what you spend' allowances like utilities, rent / mortgage, car insurance, which will need to be proven with bills, receipts and the like.
You need to sit down and declare what you actually spend --- the IP will advise if it is outside the guidelines. Sometimes there are good reasons for this which will be considered, for instance, medically required special diet / allergies requiring more expensive foodstuffs.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk
Have a look on Google. There are 'guides'. It's been a while since I did mine but I went for the maximum guide amount on everything and then some as my work travel was higher than the guides. I think the only one they beat me down on was cigarettes. I put in £240 I think as that was roughly what we were actually spending. I think they knocked that down by half. But pocket money for the kids, school trips, everything else on the list, I put down and I can't remember any of them being knocked back.
Let them argue it down. If you go in low then you're going to be the one who has to argue if you need it raised. I don't think there are hard and fast rules so it's a bit of a dance from my own experience. Look carefully at every single bit of information you can find and use it to your advantage. I would go in at the highest guide value. I have no idea why there is a range. Are some people allowed to shop in Waitrose whilst others have to buy the value brands from Asda?