It involves a bit of admin, they have to request your training records
off the old school, and will probably mean you have to do a number of revision flights to get you up to speed
OK Alex, I should have qualified my reply. If you swap before 'checkpoints' are achieved it will cost you a lot more money, and by a lot more money, I mean......
a lot more money. The next school you go to will want to check your progress i.e. that what's in your log book has actually been learnt proficiently. You will then continue on the syllabus. If you then start at
another school before you have reached a 'checkpoint,' as above.
The admin involved is not seamless, paperwork gets lost, delayed etc, some schools get a bit shirty when you leave, which means you wait...........then pick up your flying again, you may have to revise stuff that you have previously learnt.
If you get transferred a lot an alternative is to use your holidays to reach a milestone (GFPT) then transfer to another school for your PPL. Once you reach PPL and start your CPL there is much more flexibility.