Edited, cause I've just realised the whole link doesn't show up in the post, and unless you're sadly stuck at a navynet terminal on a Friday evening, as I am, it won't work.
If you go to the HMNB Porstmouth homepage, look at "Help & Feedback", select A-Z and go to 'M' for maps its there.
NWW is pretty much about the furthest from any gate as it goes if you are walking, but is okay in a car as you park up in the main car park near middle slip and you can easily bimble to it from there (5 mins).
Fountain Lake is probably THE worst one to be berthed at though and is probably Pompeys answer to Rubble Jetty in Guzz.
Actually we're on 1 Jetty at the moment (in Guzz of course) which is right next to Rubble.
At least you can park your car near the ship though, no parking fascists in South Yard
We are only coming to Pompey for a weekend though, most will probably go back to Guzz, although to be honest I don't see the point after saying bye to the kids.