You really have to apply to both. Its extremely competitive and there are no guarantees....I know people that have been TAs for years and they can't get into a GTP. I have a load of experience and 2 degrees (a BA and MA) and I didn't even get an interview (for history). By all means go for it. I have a place for a PGCE in September and I have a 14 month old. I'm terrified of the workload but I have to do this; its been my ambition for years. Good luck! Get some school experience in if you can, I know its hard but it'll really help your application.