Whilst I can't recommend anyone for the turbo rebuild, I can say that if I were doing that particular list of jobs I'd whip the engine out!
Taking the turbo and inlet manifold off first (together with the studs holding the manifold to the engine) makes getting the engine out far easier as there is more fore/aft 'wriggle room'.
Whilst that is being refurbed, the rest of the engine out stuff is logical (the right hand side has to come off to do the timing belt, and the left hand stuff has to come off to get the gearbox out to do the clutch.....together with driveshaft work.....
... so getting the engine out means you can leave the gearbox (and driveshafts) as they are.
Rock Auto list a selection of clutches, but they aren't always where you would expect to find them...... ie, don't look for a clutch for the Impulse Turbo, as they list ones for that car, which are smaller than the turbo elan clutch (but the same as the NA one). Lotus chose to use the slightly larger clutch plate/cover from Isuzu, and it is the one listed for the 1992 Isuzu Stylus 1.8....... it is 8 7/8" diameter, NOT 7 7/8" (either will physically fit, and no doubt would work.... but the smaller one was deemed too small by Lotus to cope with the torque requirements of the car under heavy accelleration).
A quick look gives a choice, and one of them is SACHS K7004701 - so a cross reference may well give you far more choice elsewhere. (Of course, ordering from SJs / SWL or somewhere else in the UK is possible, but may not (will not!) save you any cash!
Many have used the Exedy clutches amd swear by them.....
more info
here