If the variator and/or cam belt need replacing (40,000 or 4 years) it might be easier to take out the whole lump. DO NOT RUN THE BELT ANY LONGER.
The gearbox job on its own is much same as the 1200 get the car on a lift and take off the gearbox from below. There is a bracket under the inlet manifold that foxes some folks but its otherwise straightforward.
Its worth replacing the clutch while its open and make 100% sure the clutch operating lever is not bent or worn in the wrong places.
Alfa specialists wont have any problems but wont be the lowest cost.