Enter your GPF address as the "Shipping Address" as shown below, whenever you buy from any UK online stores.

Your Name
Unit 1 Finishing House, Peel Street,
Suite UKxxxxxx, GPF-xxxxxxx-UK
Willenhall, West Midlands WV13 2BZ
United Kingdom 

To find your GPF address, sign in to your account, and it will be in the upper right hand corner.

You may also be asked for a “billing address" when paying online retailers. Use the home country address associated with your credit card.