There are a few reefs around the coast of Guernsey which are good if the swell is pumping from the Bay of Biscay, but generally it is pretty inconsistent.
Pontinfer is the most consistent, popular break has most power. It’s a north west facing break, with waves breaking over sand and rocks, best on an outgoing tide.
Vazon Bay works from mid to three quarter tide; There is a break towards the northern end with a central rocky area called Vazon reef which works at high tide. The south coast might not be the most consistent area for surf in Britain but when there’s a swell pushing up the channel it can turn it on.