I currently live in Hong Kong and would want to buy the physical edition of cyberpunk, but at around 2020 September i'm moving to england. Will I still be able to play cyberpunk or is it stuck in Hong Kong?

Congratulations on and good luck with getting out of HK before the PRC manages to fuck it up even further.

If you want a certain answer, you should probably contact support, but I'm pretty confident that you'll be fine with the DRM free version of the game.
Firstly, since there is no DRM, you could just copy the game files onto a drive and plug in the drive abroad, so I can't imagine them bothering with region-locking.
Secondly, region-locks are arguably a form of DRM, so I doubt CDPR would dare implementing it on the DRM free version.
Thirdly, once the game is in your GOG library, you should be able to download it anywhere, because you can log into your account from anywhere in the world. What are they going to do, block downloading for certain games in your library based on your geo-location data? And even if they do, you can sign into GOG using a VPN that says you're still in Hong Kong.