The tax man cometh
A word of advice from someone who has been 'investigated' by the Taxman.
Be open and honest and be seen to be trying to help them all you can, i found this approach helped me alot to resolve the problems. He may well raise an estimated assessment and ask you to prove it is excessive. At least you can avoid the penalties arising after 22 June, if not the tax (over)due. They will get round to you and when they do they will not let it go until they are satisfied that all income has been assessed and the tax paid.
No time to lose