There are numerous shops. With you in the United Kingdom, ones like NewInChess.com and Qualitychess.co.uk are not far from you at all.
Actually, those 2 are actual publishing companies.
As far as generic chess shops, probably the one you should look at is Chess and Bridge: The London Chess Center. It is a large shop with great selection like USCFSales.com, but based where you are.
There are plenty of books on the Queens Gambit. Some generic, some specifically written for White, some written specifically for Black.
Look there and post the ones you are considering here. We can tell you whether it covers Black, White, or generic strategy.
Do not rely on YouTube. I have seen those before. Some aren't very good, and others that do give decent information are WAY too shallow and do not explain everything you need to know.
I haven't seen any resources on the chess queen's gambit opening. I play the opening, and the things I know are from seeing other games or recognizing my mistakes and adjusting. I would like help to find resources for this opening for white. Can anyone advise?