Okay, I don't know if UK has lenovo or any of the ones I'm gonna mention below.
Here goes.
Lenovo usually have some diamonds in the rough. I guarantee you, the discrete GPU will die slowly and earlier than other manufacturers.
These are your best bets going with lenovo.
http/shop.lenovo.com/us/en/laptops/?menu-id=laptops#facet-11=1,2,3,4,5
Otherwise, with such high budget like yours, I'd go for msi or Eurocom.
These are pretty much guaranteed to serve high speed gameplay even at coniderably cheap prices.
msi
https/gaming.msi.com/app/find-your-gaming-notebook
Eurocom
http/www.eurocom.com
The list below can potentially go over budget.
https
/www.originpc.com/
http
/www.xoticpc.com/
https/www.maingear.com/solutions/custom-built-laptops.php
http
/www.avadirect.com/
https
/www.cyberpowerpc.com/
http
/www.ibuypower.com/ (msi department)
http
/www.digitalstorm.com/
https
/www.pugetsystems.com/
http
/www.falcon-nw.com/
STAY AWAY FROM!
Acer
Apple
Asus
Dell
HP (just for now)
Microsoft
I hope you find your dream laptop my friend....and may God bless you.