I would recommend a rod of 9 feet, that throws an 8 or 9 weight line. The new Greys range of GRX rods have the perfect model. its sold as a Pike fly rod, but it looks ideal for carp. It has plenty of power in the but...and only costs ?80. Dont be put of by the price...its quality gear. I say 9 feet because u can exert more pressure on a shorter rod.
As for reel...I use a Leeda Dragonfly 120. Its about ?40 and is a disc drag reel. I cant fault it.
For a fly line, I would recommend a double taper for delicate work and small baits such as cat biscuits...or a weight forward for distance and heavy baits like floating bollies. Use a floating line...and try and get one that is grey/brown or green. A bright orange line scares the living daylights outta them.
Leaders...hmmmm..well...about 6 to 9 feet long, preferably tapered as u want good turnover. Have a look at light Salmon leaders in 10-12lb flurocarbon. or maybe down to 8 lb if the water is not snaggy. Remember...u will not have the same stopping power as a 3 pound test curve rod, and fly lines stretch!
This set up can also be used for Pike, Chub and Tench...yes...tench :O)
Give me an e mail if u want to know any more...