I have limited time, so haven't read all replies or been to the various places recommended.
If it is of any help - we have had our narrowboat for 10 years and lack of time, confidence and knowledge resulted in our not looking after her as well as we should have.
The result is that we are now working very hard to bring her back to good condition.
We went to Caldwells - who made the windows - for window seals and advice - a marvellous company and so helpful. All windows removed, cleaned and re-sealed.
The metalwork around the windows is relevant to this post. There was significant rust around some of the windows so, before putting the newly sealed windows back in place, we had to deal with that.
I contacted a company called Boatpaint Ltd. On a Saturday morning, they replied the same day giving me time, excellent advice and the confidence to tackle the task.
We ordered Holdtight Rust Inhibitor, Owatrol Corrosion Inhibitor and Epifanes Multi-primer, receiving not just the products, but also detailed printed notes on how to use them most effectively, to back up the verbal advice already given. We were also encouraged to contact them again if we needed further help.
The job takes time but, for someone who was originally quite scared of the task, it has proven to be straightforward, effective and extremely satisfying. Still a long way to go, but the windows were very important because they were leaking and the water was badly affecting the wood inside the boat.
For the bottom, we had it done properly at Tarleton Boatyard - I cannot praise them highly enough.
If any of this is of any help, good luck.