Are you doing one of the Guadalupe White Shark trips? Just curious...
Pretty much everything about San Diego diving is here -
Divebums - A San Diego Dive Website - especially in the
local info section so I'll just touch on a few things to know. The signature shore dives are in the La Jolla area. For boat dives, the Point Loma Kelp beds are popular, there's a small wreck alley or day trips to Los Coronados on the US/Mexico border.
La Jolla Cove is extremely popular - on weekends parking is a problem after 8AM. IBDivers LaJolla is a good option for tanks nearby. Possibly guided dives also. La Jolla Shores is popular nearby as is the Marine Room.
Some of the shops they list are no longer there. All the PADI Sport Chalet's just closed permanently in the western US. Also I read somewhere that Dive California did also except for classes - shame as they were convenient if you were staying in Mission Beach/Bay. Ocean Enterprises is PADI if you need that for some specific reason - otherwise some of the shops left are NAUI.
All the diveboats leave from the Mission beach marinas for local trips. Currently Lois Ann would be on their six-day schedule so that might be a good option for you to catch a dive any day except Weds. Specify tanks/weights needed also - a lot of SD divers bring their own. The Point Loma Kelp Beds are nearby but I've heard it's a little sparse this year due to El Nino.
On the Coronados Islands trips 1/2 the dives are technically in Mexico so the boats provide US->Mexico Visas - you might check if they know how (or can) provide UK-Mexico Visas also. Thats a fun trip, not too deep and a big seal lion rookery so they'll be out to play. Read the fine print also, on some trips - esp. Mexico or the rigs, you can board as early as the night before since they pull out well before dawn so you're on-site by 8am or so.
Lastly check with Power Scuba's meet-up group. They dive locally and at the La Jolla Shores - Thursday nights and Saturday mornings. Also run trips out to the oil rig platforms - with your dive count you qualify.
Power Scuba: San Diego Scuba Diving (and Beyond)
Post in our Southern California forum also - maybe a local diver can show you around.
