If you want to research in Education (do I get it right?) then a PGCE would certainly be useful, but is not necesssary. I know a girl who got accepted for one and did really well. She had a MA in History I believe, dissertation not related to Education at all.
Her boyfriend was doing a PGCE with me and he said he always had the frustrating impression she was learning a lot more than him by doing field research, without actually getting to teach. What I see for sure, it saved her a LOT of trouble, work, and tears. PGCEs are certainly difficult, especially if you are not 200% "it's all about the kiddies"-minded.