Probably a silly question,but have you remembered to register with the tax office that you have started a business because you have to register within 3 months of starting up.
You will be liable for tax from May 08 when you started to 5th April 09,if you file online won't have to be submitted until end Jan 2010,but i wouldn't leave your first return to the last minute.
You will have to pay any tax due + 50% on account so be prepared.-John