How exactly does your system work? I mean, do most employers offer insurance? Does the average person have to go to certain doctors? Are certain treatments, medications, etc. covered and others not?
No, most employers do not offer private health insurance. It is a "perk" with some jobs, and it is taxed.
Everybody can register with a GP (General Practitioner) surgery in their area. You can choose which surgery to register with. Some surgeries are busier than others, in some areas it is difficult to get an appointment for non-emergency consultations (you may have to wait for a week or so). You may not see the same GP every time. All GP appointments are free.
You pay a set fee for prescriptions, irregardless of the actual cost. I think it is about £6.
There is a government department called NICE (National Institute for Clinical Excellence) which determines what treatments are available. Some regional health authorities provide services which others do not - this is referred to as the "Postcode Lottery" - it is all down to budgets and funding. This tends to affect expensive drug therapy for instance, and is rare.
All women have the right to free birth control - and your pharmacist does not have the right to refuse to serve you if she is a fundamentalist christian.
Waiting list times are a problem, and not easily resolved, because doubling the NHS budget would not spontaneously produce qualified nurses, surgeons, physiotherapists and so on. If you are fortunate enough to have private health insurance, or you can pay, you can skip the queue by going private - and usually see the same consultant you would have 12 months later on the NHS. Which does raise the issue of whether private health care is relieving an overstretched NHS, or just worsening care for those who can't pay.
Nonetheless, as Mike pointed out, for acute conditions or emergency care, the NHS is still excellent.