Genuine renault one was £27 from my local dealer this summer just gone. Paste isn't specifically recommended by renault, nor is there any noticeable amount on as standard. Can't hurt to put a little bit on though. For the extra 23 minutes it takes, stick it up as high as you can on axel stands. Obvious advice is obvious but the CAT isn't quite slap bang in the middle, so jack up the side it's nearest to
Best advice is make sure you've got a decent quality 1/4 inch socket set & good spanners. The bolts are done up very tight, it's often very very corroded & it's not the easiest place to get a dremel into if goes wrong. I had a few goes hammering sockets onto the corroded nut/bolt, tried (drop forged) spanners, tried to cut through it with a dremel etc. Went back the next day with a decent 10mm spanner and off it came in 10 minutes.