Sod the accountant

i've got my own limited company where i've had an accountant do my books year each year. At present i'm not working that often but my books still need doing and i feel i have been chasing my accountant in the past to get things so thought i'd do it myself this year and save £500.
I've just done my annual return with companies house and should be able to fill in the self assessment for personal tax but what about corporation tax, what form do i need to fill in and is it straight forward?

cheers