The Access Code says:
Access rights extend to canals, canal towpaths and canal embankments, but the amount of recreational and commercial use and the safety issues arising means that this use has to be managed. If you wish to canoe or undertake other water-based activities on canals, follow any local byelaws or regulations, including the Waterways Code.
Remember that canals can sometimes be confined and may contain deep water. For safety reasons, always give way to motorised craft. Canal locks and lifts are regarded as structures and so access rights do not apply. However, access across some lock gates might be possible where specific provision for access has been made.
Some people stay overnight on boats on canals and so you need to respect the privacy and peace of those living in boats. Take care not to cause alarm or annoyance, especially at night. Some towpaths can provide good access for cycling and horse riding, but when a towpath becomes too narrow or dangerous, such as where there are low bridges, then dismount. Keep dogs on a short lead to avoid causing problems for other users and for wildlife.