The National Coastwatch Institution (NCI) is an entirely voluntary organisation keeping a visual watch along UK shores.
There are manned stations on Portland Bill and on St Albans Head.
They are happy to give an up to the minute report of sea conditions near their station; follow the links for phone numbers and watch hours. They have a dedicated VHF channel, VHF 65.
Ch65 is a Duplex channel which means you will not hear other boats calling an NCI station, but you will hear NCI responses.