fredfinks :
Oh didnt see your main question. Yes, its an ITX case. It has nowhere near the internal volume of a regular mid tower. Yes that means your upgrade options are compromised. Mainly with the amount of Hard drives. However it can be upgraded.
You may not need the size if you are swapping the parts.
This is a bespoke system that probably has a premium on it vs a system of your choice made up with parts. However, its a very nice package, with high quality parts by a top respected builder so it might be a good idea to buy it and not stuff around.
Their support is probably way way better than a small chinese shop too. Yeah go for it. It will run 1080p monitors A-OK.
Enjoy the gaming
I went ahead and got that PC in the end. I think the 2TB hard drive should be okay for me, I don't tend to use up huge amounts of space on my computer. But like you said I could probably upgrade it in the future if I need too.
Will I be able to swap out/add a regular graphics card later on or will I need a smaller one for the ITX tower?
The warranty kinda sold it for me in the end, if I built it myself and it broke down in 3 years I'd end up having to buy a new computer anyway so I'm thinking of it as a long term investment.
Thanks for your help dude much appreciated