I have visited Zeebrugge once to check on the Stanavforlant fleet and those were at that time all docked at the Wachtkaai in Zeebrugge (on GE that is the upperleft quay). The area was very much fenced off then. I don't know if this is standard procedure in Zeebrugge for Navy fleets. Maybe you can see something from the Westerdam (the left pier into the sea).
The Belgian navy also own a parts of the harbour and the ships can also be docked there. GE shows an image of a French helo carrier being at the containerterminal next to the Navy part. Then it should be visible from the Zeesluisstraat!
So a lot of options are left open! Only one way to found out I guess! Sorry for not being able to help more!
Providing some simple streetnames can be of much help !
Tomorrow i will be hunting them down, together with my navigator
For others that might go, perhaps Graaf Jansdijk can also provide some view at the naval part ( source GE ).
From the Graaf Jansdijk, just past the maingate from the Naval station.
The Jeanne 'd Arc and her sister can be seen.
On the first one 5 helicopters were outside:
All III: 100, 106
Gazelle : BQP/4233 ,BQY/....
1x SA-330
If anyone has the complete numbers, please post them.