Currently on a subject knowledge enhancement course. A guy on the course got a third class degree, and has a PGCE place for next year (provided he passes this course). I also have friends who have done PGCEs in the past with 2:2s. Govt is putting a minimum of 2:2 in place for ITT for next year (cutting funding for places for people with less than a 2:2). I'd suggest not sweating the degree classification if you can improve other aspects of your application. Maybe highlight your classroom experience, your ability to reflect on good practice etc... If you don't have a good application and interview, your degree class, be it first or 2:2 won't make up the difference!