One thing to consider is the extra debt. At my institution masters courses are just a way to milk the (usually international) cash cow, also having known people on masters courses I'm not confident that the quality of teaching is worth the money paid out.
If you're sure you want to do a PGCE and become a teacher... why waste time, you should get signed up right away! I've so many friends who became teachers and not one of them dislikes it. It's hard graft but rewarding is the general gist that I get. Most universities offer a PGCE as a masters now too!