Thanks to Dharl for the link to canalplan, very usefull
dmr, there does not appear to be through route for anything other than a narrowboat, and as we are coast cruisers anyway, i quite fancy the trip taking in Caen Hill, and through London on the Thames anyway.
Out to the sea via Avonmouth would give me the choice of South and around Lands End this would take too long to do in 1 trip (work really is a problem) or North to Liverpool and across the Leeds Liverpool canal, but there is a question mark over air draught this way as well
regards Drew