thank you all for your responses. I can see that more info from me on my expected use is needed for you to guide me on what might suit me:
I'm 66 but fit & active at present. I'd welcome the exercise associated with narrowboating to keep my body working.
I don't have a house in the UK. I can store a small amount of stuff in the garages of family & I have already as I'm currently living abroad. I will skulk off to Thailand each November to avoid the dismal UK winters & return in the Spring to see the leaves come out.
I would expect to stay at pleasant moorings for a week or more, perhaps for the full 2 weeks; I want to explore the nicer bits of canals & rivers but I'm not on a mission.
I'm persuaded by comments that 50ft is likely to be quite long enough for me to liveaboard & I'd choose that size if it's no impediment to later resale. I won't be going for a fibreglass cruiser as I think it might be too fragile on canals.
I quite like the idea of a solid fuel stove as it seems cosy, although I recognise it creates dust.
I don't think I care about a washing machine; I think I'd like a quick shower every other day with a good wash on alternate days
I don't imagine I'll have visitors staying with me; I'll be fairly solitary although hoping to meet nice people along the way.
I'm expecting this boat to be sold after 2 years by which time I'll have a much better idea whether I want a new boat or a new retirement idea. Accordingly, I want it to command a ready sale. I know I'll leave it better than I found it.
£60k is all I can afford but I've no real idea whether it will take all that amount to buy a decent boat that will readily resell in 2 years; I don't really have any clue what makes a boat a £40k boat and what extra desirable features make a £60k boat. I definitely don't want to be seduced into paying £60k for a boat that I later find is really a £40k boat & that's all I can reasonably achieve on resale.
Thank you all very much for your helpful guidance so far. I've enjoyed all the washing machine discussions although I didn't expect them