Yes I always forget when these things are filmed and I'm pretty sure this was meant to be on autumn last year before Doctor Who. Though I still stand by why cast someone who is fairly well known and was before Doctor Who in such a small role? That's the problem with schedule changes as it took over a year to get Room at the Top out so it can look like overkill for some actor/actresses if it's bad timing.
I agree with Joanna being a future star as she has been good in all the things I have seen her in. Also thought it was quite funny to read that Janet was Beth in Skins who is in one of the most explicit scenes Skins ever did.