Well spec'd brand name desktop if you're looking for a fast CPU at budget price.
HP 280 MT X3K20ES
Intel Core i5-6500 3.2GHz latest generation 14nm i5 http://cpuboss.com/cpu/Intel-Core-i5-6500
Delivery free 7 day service to mainland, £7.20 3 day, £12 next day
£26.40 to N. Ireland
Hat tip to @AndyRoyd for cheapest price