Depending where you are going (check foreign office site) it can be perfectly safe to explore independently. The bonus of planned tours is you get a guide who speaks your language who generally shows you some highlights as well as your main destination. The cost of the tours will vary from around 40 euros for a couple of hours to 150 euros for a full day with lunch, it depends where you go, entry fees etc. On our Baltic cruise MSC ran shuttle busses to the main towns, that is the town where the port was, not the capital cities, the cost was 5 euros per person. We dared to try public (trains) transport in one city, it was great fun, we bought tickets from a machine which took a credit card so no cash required.
You have some time to decide which you want to do once on the ship, free guides and maps are available for each town on board.
If you give us some more info you will get good advise generally. Name the ports & we know where to start.
Royal Caribbean - Independence of the Seas - 14 Oct 17 - 7nts
Southampton : Gijon : Bilbao : Cherbourg : Paris (Le Havre) : Southampton
Now from £579pp
View All Reduced Royal Caribbean Cruises >>
Click here to see offer
P&O Cruises - Ventura - 13 Nov 17 - 11nts
Southampton : Lisbon : Valencia : Cartagena : Gibraltar : Seville (Cadiz) : Southampton
Now from £599pp Was £639pp
View More 2017 P&O Cruises >
Princess Cruises - Caribbean Princess - 20 Apr 17 - 11nts
Southampton : Guernsey : Cork : Dublin : Hamburg : Rotterdam : Brussels : Paris : Southampton
Now from £999pp Was £1329pp
View Top 10 Offers For Princess Cruises >>