Yeah looks like just the job. did both rear locks on mine a couple of months back.
 
it's not the quickest of jobs but there is a guide on here. Just get it done before the door lock goes for good, it happened to me and was a PITA to replace when you can't open the door. The lock from dealer is £100+ so you got a bargin there.
 
Nice one people thanks for the advice, last thing I want is the lock to go completely. Will do the seal while its off as im an expert at doing them now lol