Really cannot recommend going with a monthly payment plan unless you can get it for 0% interest for longer than you intend to have to pay for it. Otherwise, you'll likely be paying for it quite a bit longer than you expect. I went with your £800 budget rather than you < £1000 budget.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i5-6500 3.2GHz Quad-Core Processor (£164.28 @ Aria PC)
Motherboard: Gigabyte GA-B150M-DS3H Micro ATX LGA1151 Motherboard (£61.98 @ Ebuyer)
Memory: Kingston FURY 16GB (2 x 8GB) DDR4-2400 Memory (£49.49 @ Ebuyer)
Storage: Samsung 850 Pro Series 256GB 2.5" Solid State Drive (£97.49 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£37.98 @ Novatech)
Video Card: Asus GeForce GTX 960 2GB Video Card (£154.96 @ CCL Computers)
Case: Corsair 200R ATX Mid Tower Case (£52.33 @ CCL Computers)
Power Supply: Antec High Current Gamer 520W 80+ Bronze Certified ATX Power Supply (£54.95 @ Overclockers.co.uk)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer (£12.37 @ Amazon UK)
Operating System: Microsoft Windows 10 Home OEM 64-bit (£71.90 @ More Computers)
Total: £757.73
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-06-03 20:50 BST+0100
However, here is the build for Mesh Computers:
Fractal Design Core 1100 Micro-ATX Case, USB 3.0
500W FSP Quiet Power Supply - Bronz 80 Plus
Asus B150M-C DDR4 Intel Skylake Micro ATX Motherboard
Intel® Core™ i5-6400 Quad Core Processor (Skylake,2.7GHz-3.3GHz Turbo, 6MB Cache)
16GB 2400MHz DDR4 Memory (2x8GB) Memory Kit - Major Brand
2GB NVIDIA GTX 960 Graphics Card, 1024 Cores, DP/DVI/HDMI
250GB Samsung 750 EVO, 2.5" SSD, SATA III - 6Gb/s, Samsung MGX, 256MB Cache, Read 540MB/s, Write 520MB/s, 97K/88K IOPS
1TB Seagate Barracuda SATA III 6GB/s 7200rpm 64MB Cache 8ms NCQ
24x DVD Writer (read/write CD & DVD)
Integrated 7.1 High Definition 8-channel Audio
High Speed Network Port (Supports High-Speed Cable / DSL / Network Connections)
Genuine Windows 10 Home 64 bit inc DVD & licence
BullGuard Internet Security - Free 90 Day Trial
Standard Warranty - (Lifetime Labour,1 Year Parts,1 Month Collect & Return)
Which comes in at £799.98 inc VAT
-Wolf sends