Hi, the thumping is normal on this car.
The clutch job is pretty standard, but it does involve the removal of the exhaust system and drive shaft. I've done mine twice and it is really pretty easy. A couple of gotchas do exist, though. Flywheels are pretty much non-existent, but machine shops can resurface them. The flywheel is a dual mass flywheel, but there should be no problem getting it cleaned up in the machine shop.
Also, the hose to the slave cylinder is not available as far as I know, but possibly is for the manual transmission Jaguar S type (not the S Type R, which is a whole different beast). The slave cylinder is integral to the throwout bearing, so the hose has to go from outside of the transmission to the inside, and that is why care must be taken to not lose any parts of that hose. I know one guy had a problem and maybe lost a part for that hose and he had a bad time trying to get the part.
Other than that, it's pretty standard clutch replacement process.
The drive shaft is also unique so you should make sure that the shop you select is capable of reading. The drive shaft is telescopic with a design like a mandrel. You have to loosen the locking nut of the 'mandrel' and then slide the shaft into itself to create the clearance needed to disengage the shaft from the transmission and rear end. Because of the master technician not knowing this, I had a Ford garage working on my rear end rebuild drop the shaft and the rear end together, which bent a few things. They should also mark the drive shaft flanges to match up with where they were before the repair, and also from what I heard, but never saw, the bolts and washers holding the shaft to the trans and rear end should also go back to their original spots, due to their being used in the overall driveshaft balance scheme. I had my drive shaft off so many times that I lost the original positions, but no balance issues were ever noticed along the way.