Roy cruse is a local in that neck of the woods. (I'm also aiming to do a run to the scilly's later this year and Roy gave me excellent information, not to mention inspiration to get down there and do the trip - I'm watching the forums and trying to fit my diary commitments with a suitable weather window, not to mention wallet capacity later on this year) Roy's been over recently and advised me he'll probably be going again later in the year.
From what i can see, local knowledge is a must for your first trip out, due to the technical pilotage issues @ the scillies. It appears good cover ain't in abundance and unless you know what effects the weather has on what anchorage, you can get caught out. Drop Roy a PM, he's established on the south west ribsters scene - he'll know who's about & doing what and can probably give you heads up when the next trip out is likely to be planned.
Roy's site is also excellent and well worth a visit.