Fuel starvation problems
Oiled up spark plugs.
Loose wheel nuts
Unbalanced wheels
An internal part of the getting sucked into the engine and destroying a piston
A con rod being thrown.
Judder is a vague description! there are hundreds of things that could cause it, some are safe to continue until you can get off the motorway at the next exit, some are an immediate problem that you should pull over for straight away, a few can be ignored until you get home.
That was a question for Tambo who posted immediatly before me stating that she could use her Hazard Lights AND Indicators at the same time,
It appears you think that possible as well!
No not really Baldric, you would give the drivers coming up in your rear, the chance to back off by putting your Hazards on then off then start to move across traffic permitting, again using your Hazards, then to the Hard shoulder.
I would use my hazards to warn people there is a problem, so this would slow them down a bit, I would then get to the hard shoulder as quickly and safely as possible. Then get out of the car, and go far on the verge or any safe place and call AA.