Depending on the amount of carp in the canal this should dictate how heavily to bait although at this time of year I'd er on the side of caution. Overhanging trees are a good bet if you can bait close to them and fish relativly strong.
I was told theres a crayfish problem where I fish although they don't seem to be too much of a problem, infact I've only had 3 in all the time I've fished it.
3 or bits of hair rigged sweetcorn or a halibut pellet on the method feeder have worked well for me and my Dad, also had around 50% of my fish on straight lead. Using a skinz pellet on the hook and baiting with skinz feed pellets. Although it probably doesn't matter what bait or method you use, just find the fish and feed correctly.