Thanks for the suggestions folks. Doing a bit more looking around today it seems this isn't the greatest time to be buying a new PC - shortages on many cases, overpriced GFX cards and nextgens just around the corner. There's always 'something just around the corner' of course but now doesn't seem to be the greatest time to be buying - I imagine COVID-induced consumer demand and COVID-induced supply/manufacturing delays aren't helping either!
Games are the only thing that'll push the system and here I play for example (at 2560x1440 for the foreseeable future) modded Arma3, modded RTS (e.g. TW series) and I imagine RDR2 and some kind of openworld coop survival game will find their way onto it by Christmas!
Only other thought is perhaps this system will also be the first one that gets VR added to it at some point - not sure what requirements that places on things though! I won't OC as I'dd rather have slower/quieter fans than a few more FPS.
Anyway, if I do take the plunge and build a new system in time for the Christmas holidays here's a potential starter for ten based on an H1:
Case: NXZT H1 (£299.99 @ Scan UK) includes a PSU, CPU cooler and case fan
CPU: AMD Ryzen 7 3700X 3.6 GHz 8-Core Processor (£278.99 @ Amazon UK)
Motherboard: ASRock Fatal1ty B450 Gaming-ITX/ac Mini ITX AM4 Motherboard (£103.86 @ More Computers)
Memory: Corsair Vengeance RGB Pro 32 GB (2 x 16 GB) DDR4-3200 CL16 Memory (£125.00 @ Amazon UK)
Storage: Seagate BarraCuda Pro Compute 1 TB 2.5" 7200RPM Internal Hard Drive (£53.16 @ Amazon UK)
Video Card: EVGA GeForce RTX 2060 SUPER 8 GB SC ULTRA GAMING Video Card (£368.13 @ Amazon UK)
Total: £1,229.13
I'll use an SSD I already have but still a bit over budget so would welcome any suggestions about where to trim but
TBH the £1k budget is rough guide to keep my spending level sane rather than a strict limit - bang for buck and a balanced system is the main goal.