Hello Tyrone and Agathe
I've been doing something similar to a slightly smaller boat (40') while continuously cruising in the London area. I replaced the floor, put in a new kitchen, and have relined/insulated a lot of the cabin. It's possible but some the main challenges are logistical - getting the materials to the boat down the towpath, and getting the rubbish away. I found that having a bike with a trailer (a cheap one from eBay is fine) was essential for getting things to and from the boat via the towpath. Then you need to work out places to moor that are close to a council tip (check your councils because some - not all - demand proof of residency in the borough to take waste there), and close to some timber yards and a Screwfix. Park Royal area in west and The lea between Homerton-Bow in east, or around the North Circular in Edmonton area, are probably best for this.
I used celotex boards and a CLS timber framework glued to the steelwork of the hull and cabin, Soudal Fixall worked well for me as adhesive. And make up some big 2x2 and 4x4 squares out of plywood to get things square as if youve only worked on land before not being able to use a spirit level is a bit of a shock. all the time you spend getting things square in the early stages will pay off in making the rest of the job go faster.
Get a battery powered hoover to keep on top of the dust, and a small inverter hooked up to solar panels to charge power tools, and dont bring too many materials to site at any one time or you'll not be able to move.
Good luck with it, it's mostly enjoyable!
T