A slight note to the above....If you are using a foreign registered aeroplane (N reg springs to mind) then you have to apply to the DfT for a permit to permit flight training if the FI is being paid. If you are using a friendly CRI or FI who doesn't require payment, then that point is moot of course.
The DfT will normally issue these to owners though, there are a few hoops to jump through, like sending them a copy of the latest release to service and logbook annual evidence etc., but it is no big deal. They normally issue the permit until the next annual.
Just chucked that in for info in case anyone is interested.