Manddy has suggested a Very nice build.
3 suggestions....
buy it all from one shop, so if you have problems, you only have one company to blame.... these days I usually use amazon.co.uk
I have PC's built with £25 cases, and they are fine. Just pick one with good user reviews (Not Cit!!)
If you can stretch your budget to include a samsung 850 evo SSD, you will not regret it.