Paid flying instruction can be given in a permit aircraft, but again, by some strange logic, an examination (eg GFT) is only allowed where the examiner does not receive any remuneration. Makes sense to someone obviously
All these weird ownership rules are there to prevent flight training operations being set up around these types of planes, depriving the CAA of their CofA income. Protectionist practices really, to safeguard the bulk of the flight training business.
Of course they would argue it's done for the superior safety of Transport CofA planes that have to be looked at every 50 hrs...