You`re a bit limited if you don`t want to drive anywhere. From Crewe you can get Virgin Trains to London and connect onto the Eurostar and go to Bruges which is quite nice. You could go on the ferry to Ireland. You could also look at National Express to the West Country. A well kept secret are the Isles of Scilly. You could go to Penzance on the train and get the ferry. If you get reasonable weather it`s lovely there. Don`t write off flying until the last minute. You never know with the volcano. It`s hit an miss and you could be OK.