Motherboard: Any x470 or x570 board, Gigabyte is good
CPU: Zen 2 Ryzen - Ryzen 3600 would be good for you
RAM: 16GB DDR4 @ 3000Mhz or higher
GPU: AMD Radeon 5700 XT or maybe nVidia RTX 2060 Super or higher
SSD for hard drive

Exactly as above.

I just bought a b450 board 32 gb ram and a ryzen 3600 for 400 quid. Leaves you over 500 if you go for 16gb ram for psu, case and gpu

This'll sound dumb as Hell, but as I said above, PC's are NOT my forte...

Any PC case will fit all this won't it?

Depends on the motherboard you get - there'll be micro-ATX, mini-ITX or ATX sizes, so you look for that in a case. Most modern cases have those sizes built-in.

Is there a specific one I should look for or are they literally just the sizes :D

I guess it ultimately depends on upgradability in the future for your computer or if you value a more compact build. I'd choose a standard ATX motherboard over all the other ones. As for case, check out Gamers Nexus' run-down. I have the Lian Li O11 Dynamic since I have a custom watercooled build :P

My dude I'd buy a fucking rocking horse if you told me it'd improve my PC's performance,

I'll go with the standard ATX then xD

As stated, an SSD is good to go with for storage, but you might need to account for how much storage space you need as well. If you have a lot of games that you usually have installed at once, then make sure you account for the actual space of those games to see if you can put them there. Obviously, the more space you get, the more expensive it'll be. Especially if you get a lot of triple-A games, some can be over 100GB, which is going to take up space very quickly. For examples of games from your list, RDR2 and BL3 will take up around 175GB alone.

I'd recommend also getting an HDD for extra storage in addition: They're far cheaper than SSDs, but having the extra storage is extremely beneficial for things that you don't need the extra load speed for from an SSD, so you can give yourself additional SSD space by only having applications like games (probably Windows as well) on there, and anything else on an HDD that'd be less money and have more space on it. If you don't want to spend the extra buck at the moment, though, I'd recommend investing in it in the future when the need arises!

Thankyou!

welcome to the club hun. ive been saving up for 3 years for my new pc. but i'll be paying 2k cad . and my tech bestie is ordering it off Newegg

https://www.newegg.com/ibuypower-slate-106av2/p/N82E16883227920?&quicklink=true
I'd highly recommend something like this, a great starting point and you can always upgrade or add more components later if you'd rather not build a pc from scratch yourself.