we too had bupa as a perk of husbands job. when he finished work 5 years ago we decided not to continue it but throw ourselves on the mercy of the nhs - so far so good.
we used it quite a lot when we were in it - 2 hip replacements and associated 4 years of investigation, heel surgery, lumps in various parts of the body (me and him), wisdom teeth extraction for our kids, dermatologist...the list goes on.
however since we've not been members, we have absolutely no complaints about the nhs. i'm not sure we would have paid to be in it, but as a perk of the job - a taxable perk - it was great. i see the same surgeon for my yearly check-up who did my ops, just see him in a different location.