Floaters, blurred vision, headaches and tenderness in temple around left eye - blind in right eye from birth. Eye tests ok - any ideas as to causes?

Check sed rate. You are a bit young for this but I'd check an ESR ( sedimentation rate). If elevated consider temporal arteritis. Typically the temporal artery is nodular and tender. The diagnosis is confirmed with a biopsy of a small slice of the artery. One can see scalp tenderness with migraine but it does not typically present in the 5 the decade. See a doctor right away if you think it may be TA .
Unlikely BUT. Your age would be a huge reason why this SHOULDN'T be the diagnosis but I think if your symptoms have been present for any longer than a few days and are getting worse you should go to either an ophthalmologist or neurologist rather soon and see if anyone wants to entertain the possibility of temporal arteritis. If that turns out to be wrong (most likely the case) then, think migraine headaches.