I liked the sound of the Gourmet Pizza Place too. If you open www.streetmap.co.uk and type SE1 9PP in the postcode bit, then search on it, you will get a map with an arrow pointing to the restaurant. The map also shows the position of the aquarium over at the left hand side. The other place I mentioned is beside Waterloo Station which is on the map as well.

Let me check what time they open, just in case they are not open in the morning.