I don't know much about the Portmouth course tbh, but Bristol is probably the best university in the country for palaeontology (I may be a little biased because I studied there) since it has a very well established and active research community, and superb facilities. It is Russel group too, which is good if you want to go into research. But studying at Portsmouth would not prevent you going into research of course, we had a very succesful palaeontology postgraduate (at Bristol for both his PhD and postdoc) who had done his undergraduate at Portmouth.