Claiming travel expenses on a fixed cost basis without an travel allowance

I am self employed and earn commissions and fees. Can I claim a travel expenses on a fixed cost basis even if I don't get an travel allowance?

If you are self-employed, you can claim all your travel expenses (fuel, maintenance, etc) including wear and tear on your car. Remember to apportion though between business and personal mileage as you can only claim the percentage of your total mileage relating to business travel. It is very important that you keep a logbook to record your mileage.