I honestly havn't seen her before, not even heard the name, sometimes it's an advantage as you don't have any preconceptions of 'soap actress' or whatever. I hadn't seen David Tennant before he was the Doctor; I had seen Peter Davison (as Tristan Farnon among others) so had to relearn him a bit. And I did wait for Jon Pertwee to laspe into one of his Navy Lark characters for a while till the Doctor took over.
I must have got Little Britain wrong, the few bits I've seen of Catherine Tate looked as if they came from that, which leaves me cold, it must have been her own show.