Scottish PPL
There are regulations relating to the aircraft used for training: it has to be on a Public Transport C of A, or you have to be the sole owner if it's on a Private Cat.
It's different again, I understand, for NPPL and microlights but I don't know the rules for those.
For IMC training, it has to have at least a basic IFR fit - see LASORS for details.
I've always been in groups with "airways equipped" aircraft, and wouldn't seriously consider IFR flight with anything less (although the 75 MHz marker receiver doesn't get a lot of use in this country these days).