"Why not buy a steel barge from Holland as done on Grand Designs and then build a Helsinki Log cabin on the deck? I think it would be a grand design worth seeing. Not only would the hull provide additional accommodation but the Helsinki itself has four rooms for living in... I'm not sure what the barge itself would cost plus the mooring but the cabin is around £10,000. We can even fit the kitchen and bathrooms as well as the log cabin. It could be a very inexpensive way to have a luxury home close to London."You can find more details about cabin living here.
Photo of a floating shed in Amsterdam by Ange