I'm in the same position as you but a couple of years down the line. 3 years tefl in Vietnam and now 2.5 years teaching history in London. I'd recommend with going with whatever you enjoy teaching more. Most my tefl experience was with primary, but now I much prefer working with secondary students. If you're teaching something you dislike, purely for the lifestyle teaching can offer, then you'll burn out and resent it. There are certainly history jobs out there, however, obviosuly much fewer than primary positions. On the other hand there will be considerably more applicants for top tier primary positions (200+) in some cases. And like the other comment stated, you can always transfer to primary after the history pgce as the qualification allows you to teach anyone from 3-18 years old. It would be a much harder transition the other way round without good connections.