>fight back hard

Bad advice, especially in UK and in OP's age bracket. The UK has a sharp rise in knife incidents, moreso at younger ages.

https://news.sky.com/story/fatal-stabbings-in-england-and-wa...

it is also worth pointing out that there is an nascent increase in guns in addition to knives now. Plus fighting back often leads to academic consequences even in cases of self defence. I was placed into a behavioural management program the one time I fought back.

I'd take that over permanent brain damage any day.

Theoretically, but in the situation it's hard to percieve the threat level of your perpetrator and it can affect your education long term. Often bullies will be satisfied with only mild violence or insults, and trying but failing to defend yourself can often worsen matters and more permanent solutions are off the table thanks to criminal law.

Unfortunately fighting back in the UK could go either way, it's not like the American school bully in films, kids over here are getting increasingly groomed into criminal gangs and carrying knives etc. Depends where abouts the OP lives, but in some inner city schools especially, it could just escalate massively, sadly