There are 2 ways of doing it really, the easiest way (and it's still not easy) is a paid hide but you will need oodles of patience, maybe upto a 14 hour day (mid summer) and it's not guaranteed but you have more than a fair chance. Still the same way but cheaper, is a reserve somewhere that might have kingfishers but still no guarantees and still loads of patience required. The other way is to do some online searches, like 'Warrington kingfisher', it's suprising what will show up but you'll still probably end up at a reserve.
A third but much more time consuming way is to take a good walk along your local river, keeping out a beady eye, give it time and walk often enough, you'll find one, they are more than likely there. It's then a case of finding where they perch to fish. They like stillish , clearish water
I really doubt anybody would give away the location of a kingfisher (out of concern for the bird) that they might know of. Once the word is out, you'd be better off taking a burger van rather than a camera and by then, the kingfisher will probaly have been scared away, they are very sensitive birds. They are also Sched 1, so being at or near a nest site (as this will likely cause disturbance) is breaking the law, although that's not going to be a problem from mid September to about early February. I aways mention the Sched 1 thing as it's easily overlooked.