£200 is not enough. GTX770 or R9-270X as a minimum is worth more than that at the moment.
Simply need more money to meet those requirements. You might be able to pick up a decent used office PC for that.
With Nvidia, the first number or first two numbers is the generation of hardware. The last two numbers is the performance level. 60 is always better than 50. Super or Ti is better than the number alone. RTX better than GTX.
Nvidia
GTX 680 = GTX770 ~= GTX960 ~= GTX1050Ti/GTX1050 ~= GTX 1650. Cards below that might still be playable though, so don't ignore system that have a GTX950 or GTX1050
Any Nvidia RTX card will be more than enough.
With AMD a little harder to generalize. But larger numbers are better, and X as a suffix is better than no X. First number is a good indicator of generation until you reach 500, then they switched to 5000 and are currently on 6000 and the suffix switched to XT instead of X.
AMD
R9-270X = HD7870 = HD8870 (OEM only) = R9-370X (Ah the days of rebranding the same GPU over and over)
~= RX460/RX550 and any RX card with a bigger number will be just fine. RX5500
Just a quick look at Amazon.co.uk shows the cheapest desktop with a GTX1050 is £467, and it is paired with a relatively old 6th generation Intel CPU.