you re good for two hours approx. and don t even need to take the gearbox out, just support the engine, separate it from the gearbox and there s enough room to make a switch at least with 1.4 engine. but since no centering of the clutch disc can be done in this position (with prescripted tooling) it must be pretty well centered before tightening the pressure plate - if not the gearbox will not fit smoothly. Of course the starter engine must go down, disconnect the battery before, and the most of the job is done from below.
piece of cake