You can fly around the water side at 150m from the tower but there are risks. You need to make very sure you don’t get cut off by a no fly zone firstly. You also need to consider the passing ships underneath, whose upper decks can get quite busy on entering the port which increases the risk. Flying over the land around Gunwharf would be considered a congested area so not allowed without specific insurances and approval.
Having spoken to the guys at the spinnaker tower I have a pending permission when I do my PFCO next month to take off from the base of the tower and film to 50m. This is subject to working out a cordon plan with the Gunwharf management and Harbour master. Will be a really great vid though!