Fishing in lakes, canals and rivers is subject to a few rules. First of all, aged 12 upwards, you will need a rod licence (which, in fact, covers two rods). Rod licences must be purchased before arriving at the fishing site; they are available from post offices in England and Wales, by telephone or on ‘line’ at www.environment-agency.gov.uk/rodlicence. The fine for fishing without a rod licence could be as much as £2,500.
A rod licence is not the same as a fishing licence. Permission to fish needs to be obtained from the angling club or owner of the fishing rights for the water you wish to fish in, for which there is usually a fee. All fishing rights in non-tidal waters are owned by a person or entity - there is no free fishing on any Canal or River Trust-owned fishery – and being allowed to fish does not entitle you to kill or cook your catch. It is also illegal to fish using a net, under UK law.
If you have hired a canal boat and you want to fish from it when you are moored, you will need to find out who owns that section of waterway and check whether fishing from the boat, rather than the bank, is allowed then purchase a day (or season) membership of the controlling club.