Most lenders are happy with 2 years books nowadays but this is still going to be a problem for you as they would also want to see 2 years SA302's (receipt from HMRC for tax paid) for completed years and you can only supply 1 year.
There are a couple of lenders out there that will allow you to effectively self assess for the second year but they would want to see strong trading figures for the first year to allow this and you will need to provide spotless bankstatements and your credit would have to be strong too, if you have any blips then they will decline.
Go and speak to a mortgage broker and you may be able to be placed with a lender like Aldermore. I think they can only be accessed through broker and not available in any other method....I might be wrong on this though. I have never used them as they are not available to applicants from Northern Ireland