Hope I get something back in April 
If you're on PAYE, you shouldn't get anything back, because your taxes should be correct every month (that's the great thing about the PAYE system... you don't have to worry about your taxes
).
The only reason you may get a refund or may owe money is if your tax code is incorrect (i.e. if you're on the emergency tax rate (which I think is 647L for 2010/11) or the basic rate (BR) and it turns out that you should be on a different rate), but you don't have to wait until April to find this out - you can just call your tax office now and check with them if you're on the right code (if you've paid too much, they should send you a cheque in the mail, or you may owe them money).
I was mistakenly on the BR tax code for a year between July 2005 and July 2006 and when I realised this (in July 2006), I called the tax office to correct it. Within 4 weeks, I received a check in the mail for £1,500 (for the 2005/2006 tax year) and then I had the tax for the 2006/07 year (up to July) credited on my paycheques for the next few months until I had received all the money back (I went from full-time hours to only 7.5 hours a week in September 2006, so the tax had to be adjusted).
You can read about the different tax codes here:
http://www.hmrc.gov.uk/incometax/codes-basics.htm and here:
http://www.hmrc.gov.uk/incometax/emergency-code.htm
