I have this health plan but haven't needed to use it.
Several friends have made use of it for appointments and tests.
Not sure what they would cover in the way of procedures, but it does cover certain procedures, but at the very least it would get you way up the NHS list and could show if you need seen urgently.
Yes, doctor has to confirm the NHS waiting list but I think it only has to be longer than 3 months...or something like that.
I happy to keep paying it.