As Daffodil said, you do need to be careful about buying antibiotics over the counter, as they aren't personally prescribed.
If you have a prescription from the UK, take it to a chemist here,(the best is opposite the new Migros (old Tansas, Gima in Fethiye) they will try to find the equivalent.
I have a history of chest infections, the tablets that I take are 1000mg. I won't give the name.
The best place to ask for any medicine is the chemist opposite the new Migros in town, he is a fountain of knowledge, and very trustworthy.