Am I eligible for a PGT if I am doing an M.Ed. after a B.Sc. and a B.Ed.?

No, unfortunately, an M.Ed. after B.Sc. and B.Ed. does not qualify you for PGT positions in most cases. For PGT, you typically need a postgraduate degree in the specific subject you want to teach, in addition to a B.Ed. 

However, you might be eligible for TGT (Trained Graduate Teacher) positions with