If this is for the tax year 2013 - 2014, you need to get your ass in gear, 'cos the deadline for self assessment payment is today.
In reply to your question, I'm not 100% sure. I would assume that you'd be able to claim something back, even if it's just the interest.
In all honesty, use an accountant, they're not that expensive (mine cost £120 for the year) .... it'll save all the subsequent problems that could arise from filling your tax assessment form out incorrectly .....