There are some good waves in Sardinia - Capo Manu is probably the best.
Went a few years ago late September / early October for 2 weeks, got 1 swell which lasted 24 hours, but Capo Manu was firing with only a 8 out. One of those days, flat in the morning, head high plus in the afternoon and flat the following afternoon. Nice place for a holiday but I think the surf is inconsistent so not really a surf only destination
There is an Italian website www.surfnews.it
, which has some decent info on Sardinia but all in Italian.