I hope the prices didn't change too much. Generally I try to make partlists less than a week before ordering for that reason.
Can't blame him for waiting until after the exams though, getting a new pc right before that surely wouldn't have helped his grades.
Yes, 100£ more can definitely be put to good use here.
Keep in mind that the SSD also needs a slot, but fits in the bottom slot even with a 200mm GPU installed and the top slot is completely unaffected. So the external/5.25" bays still would've had room for more. The HDD bracket does complicate the assembly though, so I would've done the same with the added budget.
The 850 Evo is a bit faster than the SL308. I have no idea why the 500GB version is cheaper than the SL308 500GB, but definitely would've made the same choice.
Is he going to use the USB 3.0 ports on top of the case or rather the USB 3.0 ports at the front that the card reader will provide? A mobo with 2 interal USB 3.0 headers will fit neither the budget nor the case. So he'll have to choose which ports will be connected. If he's fine with using the case's own ports at the top he can save a few quid and get the version of the card reader without the additional USB 3.0 ports.
On that note, an upgrade to a mobo with 4 RAM slots is within budget and makes adding additional RAM later possible. I chose the ASRock B350M Pro4 because it comes with 2 PCIe x16 slots instead of one and angled SATA connectors are a blessing for cable management. However there's only 4 of them (instead of the usual 6, instead there's 2 M.2 slots instead of 1) so if your father plans on using more than 4 SSDs/HDDs with none of them using M.2 slots the Asus Prime B350M-A might be the better choice.
RAM prices changed so I was able to replace that with something cheaper and faster.
PCPartPicker part list / Price breakdown by merchant
CPU: AMD - Ryzen 5 1600 3.2GHz 6-Core Processor (£195.42 @ Ebuyer)
Motherboard: ASRock - AB350M Pro4 Micro ATX AM4 Motherboard (£75.98 @ CCL Computers)
Memory: G.Skill - Ripjaws V Series 16GB (2 x 8GB) DDR4-3000 Memory (£116.77 @ Amazon UK)
Storage: Samsung - 850 EVO-Series 500GB 2.5" Solid State Drive (£131.94 @ Aria PC)
Storage: Toshiba - X300 4TB 3.5" 7200RPM Internal Hard Drive (£116.97 @ Amazon UK)
Video Card: Asus - Radeon RX 460 2GB Dual OC Video Card (£73.00 @ Aria PC)
Case: Fractal Design - Core 1500 MicroATX Mini Tower Case (£50.65 @ Amazon UK)
Power Supply: Corsair - CXM 450W 80+ Bronze Certified Semi-Modular ATX Power Supply (£48.39 @ Ebuyer)
Operating System: Microsoft - Windows 10 Home OEM 64-bit (£83.94 @ Aria PC)
Other: CSL 3.5" all-in-one USB 2.0 (High Speed) card reader (£7.85)
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-06-24 19:02 BST+0100