I currently have an intermittent ABS/TC failure which is staying at the same level of intermittent-ness
Before i start removing the skin from my knuckles getting the main unit out is it possible there could be a fault with one of the ABS sensors/wires on one of the wheels ?
It seems that the ABS/TC lights are off when the car is cold but after 10-15 mins of driving they come on and the speedo fails, also the power steering dosent always go heavy and the speedo needle blips from time to time 

Classic ABS ECU failure symptoms. Mine did that to start with before being on all the time.

You can get a S/H one for not much money but in my experience they fail fairly quickly (all about the same age now). For about £125 you can get yours reconditioned via BBA Reman darn Sarf or ECUtesting in Nottingham. Turnaround is pretty quick.