In general, Brits don't bother to hire a specialist to sort out their taxes as it's usually all sorted out by your employer/payroll. People who have worked for a full year and are not entitled to any kind of refund do not even need to file taxes, as far as I know. The only person in my family to fill out tax returns/forms is my dad and that is only because he is self-employed.
I'm not sure if the situation is different for non-Brits, but all I had to do to get a tax refund last year (I was on the wrong tax code) was call my tax office, send off my P60 and within 2 weeks, they sent me a cheque for £1,500 for the previous tax year, and all the refunds for the current year were just credited on my payslips. No forms to fill in, just a 10-minute phone call!
However, it may be different if you didn't work a full year - there could be forms to fill in, but it shouldn't be anything you can't do yourself fairly easily, hence there being little need for a specialist to do it for you. As a student I had to claim my tax back from vacation work - this consisted of sending off my P45 and filling out a 1-sheet form (a couple of tick boxes and a signature) - it took five minutes to fill out!