How can I upgrade my low end pc??

So I bought this pc a few years ago from cash converters for about £270 because I was young and in a rush to get a pc. Me and my dad didn’t know anything about computers and we were on a tight budget so we just bought what we could. Now I know how outdated my parts are so I’m looking to upgrade…

I am looking to play games like Fortnite, CS2, R6, and maybe some higher end Rockstar games. 30-60 fps is perfect for me and I don’t play competitively, I just want to have a casual gaming pc. I also have an Oculus Quest 1 that I haven’t been able to use in a while but I’ve always wanted to try connecting it to my pc to have more games to play on it. (Atm I can only run Valorant on the lowest settings, Google, and Roblox when it feels like it.)

I want to stay around a budget of about £200 for my upgrades and I’m happy to look for second hand deals anywhere as long as I know what I’m looking for. Thanks for any suggestions!!