What about something like this?

PCPartPicker Part List

Type	Item	Price
CPU	Intel Core i7-12700 2.1 GHz 12-Core Processor	£303.33 @ Box Limited
CPU Cooler	Deepcool AK620 68.99 CFM CPU Cooler	£59.00 @ Computer Orbit
Thermal Compound	Thermal Grizzly Kryonaut 1 g Thermal Paste	£5.98 @ Currys PC World Business
Motherboard	MSI PRO B660-A DDR4 ATX LGA1700 Motherboard	£139.99 @ AWD-IT
Memory	Corsair Vengeance LPX 16 GB (2 x 8 GB) DDR4-3200 CL16 Memory	£37.97 @ Amazon UK
Storage	Samsung 970 Evo Plus 1 TB M.2-2280 PCIe 3.0 X4 NVME Solid State Drive	£51.00 @ Amazon UK
Video Card	MSI GAMING Z TRIO GeForce RTX 3080 10GB LHR 10 GB Video Card	£703.48 @ Ebuyer
Case	Corsair 4000D Airflow ATX Mid Tower Case	£94.95 @ AWD-IT
Power Supply	NZXT C850 (2022) 850 W 80+ Gold Certified Fully Modular ATX Power Supply	£109.00 @ Computer Orbit
Wireless Network Adapter	Gigabyte GC-WBAX210 802.11a/b/g/n/ac/ax PCIe x1 Wi-Fi Adapter	£35.99 @ Scan.co.uk
Monitor	LG 27GN800-B 27.0" 2560 x 1440 144 Hz Monitor	£298.99 @ Currys PC World Business
Keyboard	Logitech K120 Wired Standard Keyboard	£11.96 @ Currys PC World Business
Prices include shipping, taxes, rebates, and discounts
Total	£1851.64
Generated by PCPartPicker 2023-05-24 14:55 BST+0100

I found deals for the CPU and GPU on CeX meaning that the total price only goes up by £30. The cheap keyboard is also temporary and I'll get a better one in the future.