what conditions are not covered by the NHS?

All conditions are covered, and most treatments other than experimental. Some things aren't covered such as chiropractic or physio, but physio, in particular, CAN be got on the NHS if it is in relation to an on-going condition or sudden injury. Eye tests are not free, unless you are a child, disabled or elderly, your glasses are also not free. Dental work is not free but is at a reduced amount. You don't pay for your medications but pay a dispensing fee per prescription to the pharmacy; if you need lots you can prepay a card (about £120) and fill as many prescriptions as you need for a year. Low income people can apply for reductions, and the registered disabled will get their meds free.