OK - thanks for replying!
I'm really sorry but I have no idea what a 'career RA' is 
A bit of back-story which might help:
After graduating with a Psychology degree, my intention was to pursue a career in Educational Psychology. At that time, the requirements were this were a Masters, teaching qualification and 2 years teaching experience. The year in which I obtained my Masters in Education, the requirements changed. As such my Masters, teaching qualification and teaching experience are apparently now deemed unnecessary for a career in Educational Psychology; it now requires a PhD instead.
However, having remained in teaching for a number of years (part-time whilst I had my dc), I have realised that I don't want to be an Educational Psychologist as such, but that I have a real passion for understanding how classroom practice can and should reflect what is known about how children learn.
So with a BA in Psychology and an MA in Education, and considering my area of interest, any PhD I pursue will inevitably take a very cross-disciplinary approach.
So, in short, I suppose I don't really know what path it would take me on. I went to a PhD open day recently and didn't even know which talk to attend, as Psychology fell into 'Sciences' and Education into 'Social Sciences'.
I suppose if my research could eventually inform educational policy in some respect, then a career in that sort of thing might be good. But I don't even know if jobs like that exist! Or if I am shooting waaaaaay above my station!