I recently sent a couple to Dublin and London for their honeymoon and they did not do the guided tour which is exactly what I would recommend for a honeymoon couple. The cost aside, there are too many things that will be out of your control and this is the one time that you really want to make sure that you can go with the flow of your newlywed hearts!
There are other ways that you can keep the cost down and with a travel agent you can let them do all of the research for you (that's what we are here for)! I don't charge any fees for research and encourage all contacts to keep us in mind for that purpose - even if they are not booking with us!
The couple that I sent to Dublin booked at a good time and received a city tour for free with the package that we put together and then I sent them e-mails about the area and "must-see" and "must-do" things in the area. They were really interested in rock'n'roll history so I sent them some information about tours that they could do related to the history of rock!
Travel agents can match most of the online pricing that you can find out there (and I usually do a good search for you to make sure that you are getting the best price) and can be super helpful with the research! I strongly recommend for any Europe travel. I would love to help more and I can usually get quotes and information with 24-48 hours so feel free to e-mail me at
aprilandmatt@allabouthoneymoons.com!