I know what you mean, every busy dual carriageway/motorway is the same.
And it's no more ok for them to drive like that than it is for any car driver to expect everyone else to get out of the way when they want to do 85+ everywhere.
The trouble is, that everyone believes that they are exclusively right whilst thee rest of the world is completely and utterly wrong. Ridiculous 'adaptive' speed limits, smart motorways and that most drivers are complete morons once on a motorway all serve to compound the problem. Removing limiters and the NSL would actually allow the network to work better, but neither will happen.
Personally speaking, I will actively undertake a slower vehicle, regardless of what I am driving, but only to pass them within the limit and only to avoid moving three lanes and back (not the same as passing everthing at any cost).
To answer Kevin's point, I believe there is a section of the highway code that suggests removing yourself from a situation that you find intimidating.