Oof ... a PoA is a bit of a sledgehammer to crack a nut for many people, especially those who still have a perfectly fine mental faculty.
Most UK financial companies will have a third-party authority process. Its the sort of thing used to give professional advisors access to the account, but there is absolutely no reason it cannot be used to give other sorts of third-parties access.
The core difference is that a TPA is technically temporary (and thus will need to be renewed on a schedule, typically annually), whilst a POA is a more permanent affair and that's why a POA is a pain in the rectum to setup.
Most UK financial companies will have a third-party authority process. Its the sort of thing used to give professional advisors access to the account, but there is absolutely no reason it cannot be used to give other sorts of third-parties access.
The core difference is that a TPA is technically temporary (and thus will need to be renewed on a schedule, typically annually), whilst a POA is a more permanent affair and that's why a POA is a pain in the rectum to setup.