So I know its not a deal per se, but thought it would be worth getting the word around as I've just found out this evening that I'm owed £210, and the wife is owed £517! Not a bad result for 10 minutes work - can't hurt to check.
It's easiest if you have a passport to confirm your identity. You can also process a refund from your online account too; its actually quite a nice interface (makes a change) allows you to see tax you've paid, national insurance contributions and estimated pension etc
Once logged in if you have paid to much tax, it should show at the top of the screen below your name, here is a screenshot of mine:https://s21.postimg.org/emikh2pqv/Screen_Shot_2016_09_12_at_18_01_46.png
if you need to check you're taking home the right pay you can use an online calculator like https://uktaxcalculator.org/