Awesome. Do you reckon a basic inflatable dingy with oars would suffice to get out to this, or is a powered RIB required?
At a minimum, you're looking at sea kayaks (or some form of half decent kayak) - kayaks are cooler anyway 😎 You don't even need the currents to knock you off course, a sea breeze in an inflatable is enough to get you in trouble (and often does - the RNLI is forever warning people not to go to sea in inflatable craft, even inflatable kayaks, because they are responsible for so many call outs). A RIB with a decent enough outboard will propel you faster than the tide... but anything with person power, you're going to want to plan your trip around the tides - plan to set off and get back at slack tide, especially since around the fort and rocks there will be eddys. Probably sensible to move at slack tide even with a RIB, particularly if you're inexperienced, haven't checked the tides or the weather and don't have safety stuff with you.
Stuff like this is cool and can be done by anyone with a bit of planning and knowledge (or better yet, someone going along who knows what they're doing), but it can also quickly go wrong if you haven't planned properly and something unexpected happens. Bad things can, do and have happened to people who know what they're doing.
Not aiming to sound like a dick or put you off, but you definitely want to enjoy the experience and not need rescued or just have your explore marred by the anxiety of, fuck me we nearly died.