If you want to be a Post graduate teacher in any of the subject then you need to have the PG degree in that subject. Now if you are going to do MA Geography then you can become a PGT Geography but you need to complete the course of BEd as it is mandatory for the PGT teacher. The maximum age limit for the PGT is 40 years.

So not only completion of MA will be enough, but you also have to complete the BEd course as well.

I hope this helps. Wish you a great eve!