Pleasure! I know so many people that don't do it, and the queue at the HMRC always looks worse than it is, but free money is free money! Even if I claim 10 quid back on a trip, it all adds up...
If you are a resident of another country (i.e. have a visa in your passport), when you buy anything in the UK over about GBP 40-50 (different shops have different rules), ask for "tax free shopping" - lots of shops have the tax free logo in the window. Some places like out of town retail parks such as Bicester will print you a tax receipt there and then - you just have to sign it in front of them and fill the other details in later (date of entry and exit into the UK on this trip, passport number and permanent address in the UAE), and others like dpartment stores will ask you to take your receipts to customer services to process it.
Then, when you get to the airport, [b'>before you check in,[/b'> (as they can ask to see the goods, though I dont know anyone that this has happened to, apart from electronics) you go to the HMRC counter, hand over your tax forms/receipts, and 10 days later the VAT (minus an admin charge) goes back on your credit card! You generally end up with 10% back, which for a few minutes of form filling-in, is a darn sight better than the government getting it!
Everything I use is cheaper in the UK... You also get the buy 2 items and get a whole load of free stuff offers, samples from department store counters (go ask - they do give them to you) plus the added bonus of 10% tax back if you have your residence visa for here :)