Either a new seat cover (new seat wouldn’t be necessary), or find an upholsterer near to you (Liverpool area?) who could replace the damaged part with matching fabric. A new seat cover is likely to be quite expensive though.
A quick Google for ‘car upholstery repairs - Liverpool’ returned the following matches - there are others; this was just the first three;
- Autotrim Merseyside; Knowsley Industrial Park, Ashcroft Road, Liverpool (no website)
- Liverpool Coachtrimmers -
https://www.liverpool-coachtrimmers.co.uk- Auto Interiors; 56 Norfolk Street, Liverpool (no website)