First Build, will it work well? Could I improve?

It will work... What is your major usage?
My comments:
1. 1600 is better bang for the money as it can easily oc to 1600X, and comes with a cooler
2. cooler is way overkill, that is more for I7-8700k...
3. RAM can be faster, Ryzen loves
4. Small SSD is not worth it, get a 250gb
5. Case can be cheaper
6. PSU can be better
7. MB can be cheaper

My edits with similar budget:

PCPartPicker part list / Price breakdown by merchant

CPU: AMD - Ryzen 5 1600 3.2GHz 6-Core Processor (£178.50 @ Amazon UK)
Motherboard: MSI - B350M BAZOOKA Micro ATX AM4 Motherboard (£71.61 @ Box Limited)
Memory: Patriot - Viper 4 8GB (2 x 4GB) DDR4-3200 Memory (£83.97 @ Ebuyer)
Storage: Samsung - 850 EVO-Series 250GB 2.5" Solid State Drive (£86.98 @ Amazon UK)
Storage: Seagate - Barracuda 2TB 3.5" 7200RPM Internal Hard Drive (£53.50 @ Aria PC)
Video Card: MSI - GeForce GTX 1070 8GB Video Card (£318.24 @ Amazon UK)
Case: Phanteks - Eclipse P300 Tempered Glass ATX Mid Tower Case (£51.95 @ Aria PC)
Power Supply: SeaSonic - 520W 80+ Bronze Certified Fully-Modular ATX Power Supply (£67.10 @ Alza)
Total: £911.85
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-10-18 00:39 BST+0100