Hi Gill
Without buying the relevant Admiralty Charts I can't think of where you could attain this info for free, apart from asking some of the local sailors. However, as with the the recent A Classes I discussed tides during the skippers briefing. There's really not a big issue with tides in the Bay unlike some places I've sailed!
During the GC we will be racing during a Neap tide cycle so the tidal strength will be negligible as compared to areas of higher wind pressure or wind bend over the course. Therefore, tides shouldn't not dictate your tactics.

Some photo's from last weekends A Class Nationals are now on the MYC website. I.m still waiting for the one of me infront of Chris and the rest of the fleet to be published <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />