Launch at Sandy Lane, Chester. Navigable for around 1 mile downstream through the city centre to the weir and around 15 miles upstream to Farndon Bridge. Going up river you pass through a very nice country estate (Duke of Westminster I think) and in and out of Wales as the River forms the border. Once you get to Farndon Bridge there are some nice pubs on both the English and Welsh side of the bridge. It costs c£100 for a yearly licence but day licences are available.
Watch out for the skiffs from the rowing clubs. They never thank you when you slow down, shout at you if you don't and don't care about the wash from their attendant boats!