Leroy anything that is a real cost against your share trading (including education such as books etc) can be claimed. Brokerage, computer costs, etc. You can even claim a pro-rata percentage of your broadband and electricity bills. Just be very wary though of thinking of charging yourself "rent" for your office in your own home. If you charge rent then officially part of your principle place of residence is used for investment purposes and they can sting you capital gains tax on that percentage of the sale of your property.
IMPORTANT: There are differences between a "trader" and an "investor" for the purposes of tax returns. A trader's profit and loss are treated as "income" and an investor's are capital gain or loss. Accordingly, there are also differences in tax deductions. It's complex and worth a good account's advice. If they suggest charging rent then you need a new accountant.
