Highway code rule 277 says (in the context of driving on a motorway and having a breakdown and safely making onto the hard shoulder):
DO NOT attempt repairs on your vehicle
the assumption being that you have a working mobile phone, or can safely get to an emergency phone.
https://www.highwaycodeuk.co.uk/breakdowns-and-incidents.htmlI have certainly changed a wheel on the M3 when I was much younger. But there are many things I did when I was younger that I would never do now.