benifits not.

[fazersharp]

you can claim your VAT back, claim for heat/light, fuel, tools, clothing, phone/internet, repairs and all manner     

If you are claiming back VAT - as you put it (even though you don't claim it back ) because that also means that you have to charge VAT on your goods and services and then pay that VAT that you have collected to the inland revenue, which means that you just end up being an unpaid tax collector. Also you can only claim the vat on things needed to run your business.
Same gos for light, heat, fuel - only what what is used for the business, so if you use a room in your house for an office and your house has 10 rooms then you can only claim 1/10th of those running costs, further more if that room is also used for something else than the amount to be claimed also has to be reduced by the non business use amount.
Same for a car if you also use it as the family car then you can only "claim for the business use part.

And this from the gov website "You can’t claim for everyday clothing (even if you wear it for work)."