Two thousand pounds to learn to fly skydivers? That's insane. For five hours of training? (What could they possibly cover in five hours..that couldn't be covered in one??) Once you've spent this sum of money, how much are they going to pay you to fly jumpers?
Flying skydivers isn't exactly rocket science. One really ought to get a few jumps in and a first jump course, but it's not necessary...and as for flying the airplane...if one understands airspeed and the rudder, and proper engine operation...then there isn't a lot left. Jumpers in tow, pilot chute or open pack in the airplane, and mass exits following an entanglement...and you're done. Spotting isn't exactly complicated, communication is no different than any other flying, and it's a climb to altitude over the field and then a descent. Again...not really tough stuff.
I've jumped a fairly wide variety of aircraft, as well as piloted jump aircraft in various operations...and haven't really come across a situation that requires five hours of training...especially for something like a light Cessna 182 or 206.
As for needing a rating to fly jumpers...