I did mine on the drive by myself to remove the pre-cat. It's awkward, but would be easier if I did it again. Getting to the bottom two turbo bolts is fiddly, but ok if you've got a good selection of tools. One of them is easier to get too from underneath. Some people have trouble getting the turbo bolts off and snap the studs, however, mine where fine.
My clamp at the back was annoying as the nut was facing the top of the car and rusty, so again hard to get to and then free up.
Then I had trouble disconnecting the O2 sensor. It probably took me the best part of 4 hours, removing and replacing.
The bolts were fairly expensive from TPS about £5 each I seem to remember.