I am not sure if I am reading it correctly. Link as below.
So if I live in the house for 3 years with them without owning a house, then when they turn to 65 they can gift me the house under the exemption for a dwelling house which means CGT free?
2. No. It is not they who must turn 65 before the relief is avialable; it is you. To claim this relief you have to be a "dependent relative", "dependent" meaning either that you are unable to maintain yourself due to permanent total incapacity, or that you are over 65.