Danny, I would guess that any bombing or strafing of the Channel Islands would have been very politically sensitive, given that we made no effort to defend them and evacuated those citizens that chose to leave. As long as no direct threat to the UK existed thereafter we seemed happy to leave well alone, rather than endanger those islanders still there from any blue on blue incidents or reprisals. I'm sure we kept a close eye on things, particularly if any suspected V1 works were detected.
It was only with the Allied invasion of Normandy that the Alderney fortifications were shelled (by HMS Rodney from the far side of the Cotentin Peninsular) to protect the D-Day operations. Whether we knew that Alderney was occupied almost solely by the SS and their slave workers I know not, but we certainly knew that there were plenty of British citizens on Jersey and the other islands (Wiki gives the ratio of 2:1 civilians to Germans). Best perhaps to leave both well alone until the latter finally chucked their towels in?