The tyre looks okay but I'll probably change it anyway. When I took it to the tyre shop they were able to seal it enough to inflate it but advised that it really shouldn't be used for high speed anymore.
This is the second time my Dad has managed to mess the wheel up in as many years - it was brought just before lockdown Christmas so December 2020.
I'm not quite sure of the specifics of the accident this time but it involved hitting a road island with the wheel so it is possible that the inner side received the brunt of the impact if the island was small enough. So it wasn't kerb like I had mentioned earlier.
I guess my question has been answered, do not try to repair this. I will find another and will definitely consider moving to a 16" set as it seems I'd then get more tyre meat and 16" rims seem easier to come by when I next need to replace it. I know this will happen again with my Dad's driving. He is at the point where he is considering giving up driving but there is no public transport and he has a dog so taxi's are difficult. I drove him exlusively during the dark winter months and it was difficult as it heavily impacted on my life.