Hi Bluebell,
Peas are frost hardy to an extent. They wont take extreme frost.
I would plant them out and cover with fleece and they should easily handle any frost you are likely to experience at this time of year.
Or you could just leave them for a week or so as Karen suggests and then plant them out. Their root system develop at a far greater rate than the shoots in my experience and wont really suffer from being a little pot bound.
Don.