In reply to Cusco:
It sounds like you need specs with a prescription insert (rather than putting the prescription in the coloured bit). That will also make updating your prescription cheaper in future, because it will only be a "plain" lens that needs changing, rather than the fancy bits.
If you were in Sheffield I'd suggest that you go to Eye Eye opticians https://www.eyeyesheffield.co.uk/ It may be worth contacting them anyway, to see if they can sort you out remotely, because they're super helpful and like to make sure that people get the right thing. They don't do pushy sales, and if they can't help you then they'll say so.