I agree that you need to talk to an accountant. I am biased as I'm in the trade.
If you've generated that much sales, you must have other expenses such as phone, motor, etc. At your salary level, all profits will be taxed at the marginal rate so you really should ensure that you calculate your actual profits properly. Plus, your accountants fees will be tax deductable so it will only cost you half as much!
You need to send in a TR1 etc to register for taxes. If you've only started trading, the Revenue will allow you time to organise your affairs, so use it wisely and get assistance.