This is a nice simple one to answer.
The short answer is: Yes, you can buy a laptop in the duty free shops at most international ports. For the UK, you’ll be looking to buy from one of the “Dixons Travel” outlets which are placed at most airports in the departures lounge.
Now, the longer version of the answer is that ‘yes’ you can buy a laptop duty free, but you probably shouldn’t. Even though Dixons are removing the VAT from the sale price (currently 20% in the UK), they’re actually bumping up the retail price to counteract this, so you’re usually not saving that much at all. When you think about it, it’s even worse, because it means that Dixons are keeping all of that money for themselves, rather than passing 20% of it on to the Government for them to spend on things like healthcare and education.
Dixons no longer publish the tax free cost of products on their website, which is a bad omen. You’ll also find that the model range that they keep in stock at airports is significantly smaller than you’ll find on the high street, and they tend to stick older models in the airport waiting for a captive audience to pounce on.
A better alternative would be to do some digging around online and trying to find yourself a better deal. Not only will you have a much bigger selection, but you’ll probably also be able to beat Dixons on price.