Hi,
You will need to change the lights to UK as you said. rear lights need to comply as well. I believe rear fog light needs to be on right in UK (furthest from kerb), if your car has 2 fog lights then that will be fine.
It will need to pass an MOT, which above is required for. You said there was crash damage, If the crash damaged is severe on a UK registered car you will require a VIC test. But as yours is not UK registered, so long as the crash damage has been repaired to a good standard I dont think there should be a problem.
Registration of a vehicle was £80 about 10 years ago when I last did it, an internet search will help that.
The process is a bit difficult as I remember getting tax, and MOT sorted with all nesesary paperwork, but not as bad as you are used to with Polish bureaucracy (my wife is Polish so I can comment with experience ;) ).