with the widespread risk, I think it will be more northern areas that will cop it, as UKV showing some activity in the south on sat night, but that will change closer to the time
according to the met office inshore forecast, the showers are going to be west of lands end and in the irish sea as I use the inshore forecast frequently in work
you'll be fine mate, UK ferries are staffed by the best in the world - British Merchant Navy. I wont know till i get to work weds what our course plans are