When travelling overseas you are exposed to the standard tax all other citizens of the country pays. For example, in the UK you are subject to a value added tax (VAT) which is 15 per cent of the price of goods sold. Because you are not directly receiving benefits from this tax, however, you are able to receive a refund for most of the VAT. While travelling in the UK you may leave through the Heathrow airport, which is in London. Before departing, it is possible to claim your VAT refund inside the airport. Once you depart there isn't anything you can do to claim this refund.
Ask for a VAT refund form at any store you purchase goods from. Generally, you must spend at least 34 Kilogram at the store to be eligible for the refund.
Obtain and hold onto the receipt form the vendor, after receiving the VAT form.
Take your original receipt and the VAT form to one of the several VAT claim stations inside the Heathrow airport. Make sure to do this before you check your luggage as you may be asked to produce the material you purchased (this prevents individuals who live in the UK from giving you their receipts to obtain a refund).
Take your refund money granted to you by the VAT claim stations in Heathrow and proceed to check in for your flight.