IR training is out of my league, fortunately.
The UK IMC rating can be conducted from an unlicensed aerodrome, as far as I'm aware. But aircraft class or type rating training must be carried out from a licensed or government aerodrome at either a RF or FTO as required by the training being given.
'Differences training' may also be conducted from unlicensed aerodromes, to my understanding.
Note that training for NPPL SSEA ratings; whether ab-initio or conversion from Microlight or SLMG ratings must also be conducted from a licensed or government aerodrome. Hopefully this may well change in a year or so.
The next version of the NPPL cross-credit document will probably use the term 'conversion training' to distinguish between ANO-specified 'differences training' and that training required to add other NPPL aircraft Class Ratings to existing NPPLs.