I was wondering this too. According to Google Streetview, there only appears to be a couple of options. The Costa you mentioned at the main exit to the station, in between Next and M&S. There is also a Starbucks on the opposite side of The Strand, in between Accessorise and one of the other exits from the station.
I think a look in the N.P.G ,,other than that its a general wander about ,,,,,,we generally tend to stay together, anyone goes off on their own they might get eaten by dragons ,,,,,,,,,oh no that's oop norf innit ,,,,
hope you can get there sometime during the day Nick ,,,,have you got a contact number if you need to find us ?