I suppose the dumb dog walker who copped a leger/swimfeeder in the mush on the backcast might not see the common sense of it all.
Ah, well if you were a member of the Angling Trust you'd be automatically covered for up to £5,000,000 worth of public liability.
However, it's as Windy says (and I had this problem convincing a head teacher when I was a governer of a school years ago) even if someone is trespassing and they get hurt, you could still be held responsible. Daft as it is, that is the way Britain has become these days with the ambulance chasers.
There may be a get-out for you, not sure, but - is the land also rented to you or does it belong to someone else? Example, I rent a small stretch of fishing rights from one person, but the land I fish from is owned by the city council. Anyone having an accident on that land, falling over and breaking a leg, would sue the council and I am covered by my ATr PL £5m should I hook an old woman's ear whilst casting so problem solved, I think.
Do you intend selling tickets or letting mates use it? What about boats?