The Government of the UK recently released domestic cruise travel guides during pandemic restrictions. The manual, published through the Department of Transport, outlines the steps taken during the restrictions.
In the guidelines, the Government of the UK mentions allowing domestic shipping from 17th May to 21st June on a cruise ship that can operate for up to 1,000 people or 50% of capacity, whichever is lower. The capacity limitation only applies to passengers.
Then, the COVID-19 safety guidelines will still apply. Groups of more than six people or two households will not be allowed to mingle indoors even if booked in the same group.
For voyages that allow a layover outside the UK, check to see if the place is one of the destinations permitted by the Government of the UK. The Government of the UK hopes that after that the guidelines will actually be completed and the restrictions will not be reinstated.