Ok, a quick update:
Balanced the rear wheel on Saturday, man did it need it (took 45grams of weights.) Helped a lot, no more horrible wobble.
There's still some strange sensation as if a bearing is dead somewhere, which sometimes does and sometimes doesn't go away when leaning the bike over in a corner. I also noticed that one of the front rotors is slightly warped and is rubbing against one of the brake pads each time the wheel goes around. Could this be the source of the "dead bearing" sensation?
Thanks,
Awfers