I dont know the car, but in any car its almost always possible to remove the box without removing the engine, though one of mine does seem to be an exception. The problem is that sometimes in order to pivot the engine and box combo enough to get it under the rails you need to detatch most of the items you would for removal anyway.
Your suspension strut only needs removing at the wishbone end, and that can slide out bringing the drive shaft out (make sure you catch the gear box fluid.
You will also need to drop the engine slightly. by delocating one of the engine mounts. just hold the engine with a jack , loosen the mounting bolts. lift the jack and move the engine in place and drop it alitlle.
now you can remove the box. when replacing clutch (you ight as well do it now as clutches are cheap to buy. and make sure you buy an alignment tool.
Put back together and oil.
* THats the basic way of doing it and there may be a few ancillaries to remove.
Draper make a cheap engine gearbox replacement beam. It fits across the top of the enginebay between the wings. A central threaded ‘hook and chain’ can raise or lower the engine. Much safer than a trolley jack. Have a look on ebay for a use one. I think mine was about £40. If you are near Fife I could lend you mine.