Try going on one of the custom PC builders websites , they have customizing pages , so you can play around and see what you can get for your hard earned cash . you can get a reasonable case / PSU combo for around £25 . As an example http://www.scan.co.uk/products/cit-reaper-atx-case-black-interior-with-500w-12cm-black-psu , tho you may want to get more fans . As for the rest of the gear you are looking at , all seems pretty reasonable , could try this for memory http://www.scan.co.uk/products/8gb-(2x4gb)-corsair-ddr3-vengeance-jet-black-lp-pc3-12800-(1600)-non-ecc-cas-9-9-9-24-xmp-15v . I use vengeance ram ,had no probs with it , and is slightly cheaper at £37 , SSD is ok , but I would double check that price , looks a bit too cheap .
Surface Pro 4 UK release date, price and specs: Thinner, lighter, faster with new Type Cover and Pen