I wouldn't touch a Kolink psu with a bargepole, they are cheap for a reason. Click on the product image showing the label and click on it again to zoom in and see how weak the 12v rail is and the bit underneath that says max total power not to exceed 750w. That and the abysmal 2 year warranty tells you all you need to know about the quality of that rubbish. That would be a downgrade from your current psu (High Current Gamer by any chance?). You cannot get a quality 850w psu brand new for £50.
A quality 550w psu would be more than enough for your pc. I only use a 550w psu with a similar spec pc to you and always have at least 200w spare (gaming load is anything up to 252w at the wall depending on the game).
The Bitfenix Formula series 550w is in your budget. It's a gold rated unit with all of it's 550w available across it's 12v rails and has a 5 year warranty. The downside is that the cables are all fixed.
Four pounds over budget is the Antec Earthwatts Gold Pro 550w. This is a Seasonic built unit, gold rated, has 540w available on a single 12v rail and has a 7 year warranty. It is semi modular so the main 24 pin, 8 pin and a pci-e lead are fixed but you will be using those anyway, the rest of the cables are modular.
My basket at Overclockers UK: Total: £152.04 (includes shipping: £11.10)