Not a rib cruise, but for anyone that might be interested the RNLI Poole HQ's open weekend is coming up 9th and 10th July:
RNLI HQ Open Days
There will be static displays of most / all the classes of lifeboat to walk around, as well as some of the different launching tractors.
There will also be sea survival demos (not sure this year but in the past they have done an Atlantic capsize and recover in the sea survival pool), tours of the full mission, training room and mobile simulators, and on water displays.
The on water displays are a bit limited in scope due to the location, but they usually include an Atlantic fast launch and net recovery.