Tax Refund Less Than Expected?

Can someone help, I am a student and I have just completed my final year and have just come home, I have been unable to find a job so I have signed on 3 weeks ago. During my three years at Uni I worked part time doing various jobs with tax being deducted. I have been chasing Inland Revenue for a year for refund (I estimate about �800.00). Received cheque for �53.00 today! Was is short because I have signed on? Do they ofset any JSA against a tax refund that is due. I thought everyone got tax allowances of �5000.00 PA ?