Check out Flubit. You'll save around 10% off everything you order from Amazon/Ebuyer. It's definitely a start. I've designed the build around that.

Changes -

• Better CPU, which is cheaper after Flubit
• Cheaper motherboard. Unless you are overclocking you will be fine with an H97 board
• Cheaper RAM, just as fast
• Faster SSD, cheaper after Flubit
• Removed sound card

Links to Amazon for wi-fi adapter and PSU -

• PSU
• Wi-fi adapter

This build will cost around £1050. Here are the areas you can save money - cheaper CPU (4460), cheaper mobo, smaller/slower SSD, smaller HDD, cheaper GPU, cheaper case, no Blu-Ray reader, cheaper wi-fi adapter.

PCPartPicker part list / Price breakdown by merchant