I know this is a low budget •_•"
Where would you go cheap?
What part should be bought new?
For which part is dumpster diving okay’ish?
You will have to look at the second hand market for sure, but you can probably get a decent 1080p 80-100fps medium/high build.
Something like (or equivalent):
Ryzen 5 3600
RX 6600
16GB DDR4
1TB SSD (probably not NVMe)
Whatever case
Whatever monitor, even if only 60Hz, for now
Whatever MoBo
Tier A PSU from the Cultists Network PSU tier list
You can most likely get everything used if you buy from a second hand shop that has a form of buyer protection (eBay and similar) and thoroughly check and clean and test everything you buy
I’d get a Steam Deck with that money.
New: Motherboard, Heatsink, and PSU
Used: CPU, RAM, GPU, and Case
The majority of components you find on the used market are pulled out of working systems and will be just fine for years to come. I only recommend buying those specific items new so you are guaranteed to get all the accessories that come with them.
definitely used at that budget, local if you can, go for older gen cpu to leave room for gpu, like 8th gen intel or ryzen 1600, with a 2070 or even better
600 British pounds is ~771 USD If only new parts were picked, following the https://www.logicalincrements.com/ guide good tier
GPU: RX 6600 $200
CPU: i5 12400F $148
HSF: Peerless $35
Mobo: ASRock B660 Steel $120
RAM: 8GB DDR4 $24
Hard Drive: 2TB $52
M.2 SSD: 512GB $42
PSU: SeaSonic 500W (B) $60
Case: Pure Base 500 $80
Personally, I would change this to get rid of the Hard drive to free up ~$50, putting the money into a higher capacity M.2 if needed
I think you would probably be looking at 1080P gaming, and I don’t think this built will be super upgradeable (DDR4 RAM, Intel CPU) but I think you would be able to play games at a reasonable framerate