[gpderetta]

All employer provided healthcare setups I have encountered in the UK do not even offer a GP replacement service [1]. You still need to go to your NHS GP and get an open appointment and then the insurer will redirect you to an approved service (where you will indeed get a faster appointment). Also most insurers do not cover most chronic problems (you'll have to fallback to the NHS) and are really meant to cover just acute issues.

edit: and of course you'll rely on NHS for any emergency.

[1] at least not without paying out of pocket for the significantly more expensive premium coverage. Some now offer phone consultations but you still need to go to the GP for referrals and prescriptions.