I’m studying computing for games at university so I really need a good PC to work on while not in the classroom. Can I make a good PC for development in unreal 4 with a £900 - 1300 budget? I would like to be able to play games on it too. I’ve made a build on pcpartpicker.com (https://uk.pcpartpicker.com/list/tst4TH), It seems like a pretty good build but I’m not sure if I’ve balanced it well, maybe I’ve put too much money for the motherboard and not enough for graphics card or vise versa. please help 
If you’re in the UK then try FreshTech
UK based and great prices, also decent after sales, I’ve used them several times, no issues.
No offence to richie but just looked at freshtech and the prices are not great . I use novatech and/or ebuyer As long as you are comfortable building your own pc that is .But in all honesty we all know its expensive lego . My pc works fine for dev and cost me about £500 With 900 -1300 you should be fine my only weak area is my gpu which is the gtx 760 The rest is pretty respectable including an i56500 and 16 gb ddr4 plus an ssd to boot .Long and short of it is you should be able to create a beast with your budget .im jelous lol
My advice would be to increase the memory if you have the budget, or at least change the layout so you keep two slots open for when you can afford to fill them (2x8 for now). I’m running 16Gb in my build as well and most of the time its all in use by Unreal - lightmass calculations.
I second getting 2x 8 Gb RAM modules. 16 GB is enough for most applications but no reason to limit your ability to upgrade. There is no advantage to filling all slots.
First of all for UE4 dev I would stay away from i5/i7 and swap to x99 E5. UE4 is much relying multi-core especially when taking lightmass and compiling into account.
Second would be good to start the RAM with 64, or 32 if you have a tight budget. For 16 you will struggle to build lighting for large scene with high precision, and you certainly don’t want to see lightmass failed due to limited RAM when you wake up in the next morning. Another reason of using large RAM is to create ramdisk which can seriously boost compiling time, when you working on source build.
Last, forget about EVGA supernova… Also for such spec I do not see 850W is a necessary