Hi Linda, the answer largely depends on how you feel about independant travel, and how active you want to be.
The first port of call St. Peter Port on the island of Guernsey, is quite easy as the tender drops you within a few hundred yards of the main town & there is plenty to explore on foot.
Cork poses a slightly harder issue, firstly making sure that the ship is docking in Cobh and NOT Ringaskiddy. Cobh itself is a pleasant port with lots of history (mainly Titanic, Lusitania and Irish emigration to the States). If the ship docks here, there is a railway station with regular trains into Cork so that is an easy option. However if you want to go further afield & see the Blarney Stone for example, then a tour is the best way. Also if the ship docks at Ringaskiddy, there is nothing there - well apart from a pharmaceutical company. The ships usually provide a shuttle into Cobh, but that takes about an hour each way, so a tour may be easier.
Dublin, again check where the ship is docked/moored - If adocked at Dublin a shuttle should be laid on here into the city, and there are enough things to do to take up a week, let alone your one day in port, so no need to book a tour. We can recommend a free walking tour, the details can be found at www.newdublintours.com
The tours are operated on a tips only basis, are well paced, entertaining & educational.
If the ship moors up at Dublin Bay, then you may be better off with a tour, as the only other option is to make your way to the train station & then into Dublin, not a long run, but just a bit more awkward.
The only time we sailed into Liverpool we moored in the Mersey River right in the middle of the city, but there is a new cruise terminal there now, which is a way out of town, and I don't know of any shutle/transfer system there, so hopefully someone else will be able to help.
Back over to Ireland, and Belfast. If you don't want to take a tour to the Giant's Causeway, then you should be able to take a shuttle into the City, it parks just across the road from the City Hall - I urge you to take a look inside here, as they do free tours of the Hall but you need to put your name on the list for one of the tours to be certain of getting a look around.
Alternatively once in the centre, you are only a couple of blocks away from all the dark history of Belfast, with the security gates, dividing walls, and political murals still very much in evidence. We came away from there quite moved by the experience and realisation that this 'battle' was taking place right on the door step of the City.
Next you are off to a port called Greenock for Glasgow. Greenock itself has little to offer, but you can catch a regular train again into Glasgow, but plan your day in advance as it is a busy city & you need to give yourself that hour or so to get back to Greenock station & back to the ship.
We are due in there later this month, and have discovered a free tour of Greenock which is run by a local volunteers - you cannot book, and it is on a first come/first served basis gathering in the port hall. We'll give you more details after we've tried them :o)
And so to Inverness, this is a lovely area, but there is little to do other than watch the same scenerey over & over again, so you may want to consider a tour. Although there is a train service, the easiest stops are still small villages, so not really an option here.
Sailaway will normally have a Pipes Band on the "dockside" (oh the dockside is pier out into the middle of the river) and sometime the band will come on board during the day to perform in the theater or one of the lounges.
Edinburgh is another port where you will want to check where you moor up, if it is Queensferry, then you have to take a tender into the one street town, and either make your way to the station to catch the train into Edinburgh, or to make the most of your day, book a tour.
However if you moor in Leith then the tender takes you to the shore quite close to both the City for the Castle, Holyrood Palace etc (by bus or a good 2.5 miles walk) and the Royal Yacht Britannia which we can recommend if you like that sort of thing.
And so to Le Havre for Paris. Le Havre itself is a drab gray concrete city, with a nice inner harbour & a few other ok features. However if you are going to stay in town then St. Joseph's Church (Eglise) is the highlight. The outside is as drab as the rest of the city, but the inside is a VERY different story, it is probablt the one thing to do whilst in Le Havre, apart from get out of it ;o)
Whilst it is in theory possible to take the train to Paris, DO NOT - unless the departure time is very late, as the train services are renowned for cancellation without warning. You are much better off taking either a tour which includes free time in the City, or booking a transfer from the ship to make the most of the day. Last time we went, the coach parked up between the Seine River & the Champs Élysées, next to the Place de la Concorde, along from the Louvre museum and we had a good few hours to explore.
Hope the above gives you some ideas :o) If I haven't driven you crazy & you want any more details, or suggestions, then please feel free to ask, or send us a private message.
Bon Voyages, and welcome to Britain :o)
Alan & Katrina