W11 clean install instructions
Download a new copy of Windows using the (Second option on linked page) to an 8GB (min) USB. Media Creation Tool
Boot that USB and choose a Custom Install.
Delete all UEFI partitions on the system drive (EFI System, Recovery, MSR Reserved, Primary).
Select the...
What OS is your present pc running and what do you intend doing with it, if its running w10 and you aren't going to use it anymore, then you don't need to buy another copy of Windows, which will give you avoid £100 you can put into the system