Its not about the Golf though.......its about how the HDi compares to it, which is not well tbh! 
I'll be honest, now I've got used to it again, I do prefer a lot of things about the 306 over the Golf......but trust me on this, the HDi engine isn't one of those things lol!!! Was tempted by a local low milage china 1.8 the other day....same to tax, same to insure, wouldn't cost much more more to fuel, plus the noise and the revs....mmmmmmm, but no, I'll stick with this for now lol.
And yeah that vibration isnt good, sounds loud and rough at idle too, and seems to 'jerk' at 1200ish rpm in any gear on a flat road, not sure if its missing slightly or if it is just the mount.....I know the mounts probably not good, as when we left the engine and box jacked up for weeks (when the golf failed so i couldnt get over there) both jacks dropped over time! So the lot was just supported by the engine mounts without the 'box mount for a while.
I'll be honest, now I've got used to it again, I do prefer a lot of things about the 306 over the Golf......but trust me on this, the HDi engine isn't one of those things lol!!! Was tempted by a local low milage china 1.8 the other day....same to tax, same to insure, wouldn't cost much more more to fuel, plus the noise and the revs....mmmmmmm, but no, I'll stick with this for now lol.And yeah that vibration isnt good, sounds loud and rough at idle too, and seems to 'jerk' at 1200ish rpm in any gear on a flat road, not sure if its missing slightly or if it is just the mount.....I know the mounts probably not good, as when we left the engine and box jacked up for weeks (when the golf failed so i couldnt get over there) both jacks dropped over time! So the lot was just supported by the engine mounts without the 'box mount for a while.