I generally claim for:
car and travel (petrol, tolls, insurance, tax, repairs and mot)
stationary and printing (printer, paper, inks, envelopes, stamps)
phone and internet (percentage of broadband as its a house product but my phone is a business one)
anything purchased as capital (which is normally a lot)
any business expenditure (insurance, content plus, dj club subs, music, website)
any other advertising done (facebook, google, stickers for car, business cards)