Pootle is a common British slang term for travelling or moving in a leisurely manner, particularly in a car. When used to refer to someone walking it may have overtones of their being feeble or unsteady.
It is cited by many dictionaries as being a portmanteau of 'poodle', meaning to act without any particular purpose or plan, and 'tootle', meaning to drive aimlessly around in a car. It seems to have appeared in the 1970s, but I haven't been able to locate a source. It was surely influenced by words such as potter, podder (Scots), and putter (each, in turn, descended from the frequentative form of poke). This is perhaps mildly interesting in that between the potter/putter influence and the assimilation of tootle (the frequentative of 'toot'), one could argue that this is the only commonly used frequentative to be coined in English within the last 50 years.