When people take a baby on holiday it`s because the parents want the holiday, not the baby. I`ve seen babies on the beach in places like Barbados where the sun is really, really strong and I wonder what the point of that is. They cry on take off and landing because their ears are uncomfortable and their body clock gets completely screwed and I feel sorry for the poor little things. Still, each to their own, I guess.
I too am with the don't do it crowd. We flew to Jamaica and for the whole flight there was a screaming baby behind us. Fortunately our hotel was adults only and we were very pleased we had opted for this. Other peoples kids can be a pain when you're just two adults wanting a good holiday.
I am now coming right over to the 'don't do it' side too, having realised that at six moths teething may well be a possibility, far better to have a cottage etc and space to yourselves.
I have had more than one holiday ruined by other people's children and babies screeching in the night and I detest them on flights. We avoid kids whenever we can. I don't know much about cruising, I suppose there are family oriented ones where it's not an issue for others.
With RCI the baby must be a minimum of 6months to travel, but if there are 3 days or more at sea, in a row, then it must be 12months. That probably rules out sailing from Southampton as there are usually a few sea days before you hit Portugal. Cruise lines do not provide food for babies but at 6m it will be starting eating for itself won't it assuming you are doing Baby Led Weaning. Bring your own nappies etc too. Please be considerate and remove the child immediately from the dining room or any public areas if it start making a noise....Not much of a holiday I would suspect for yourself though, and I would say it is far too young.