Been told by Nissan dealer after 60, 000 mile service that the front ball joint rubbers have split. No mention of issue with the bearings. Not too bad I thought. They say the part comes in one bit and have quoted me £1200 to replace them. Is this reasonable. Customer at the next desk to me appeared to have the same issue

Its such a scam and see it all the time - easy money for the garages.
It is possible to fit replacement rubbers if all they are is perished.
As long as they are not perforated and leaking grease or if there is any play in the joints then it is perfectly serviceable. Advise on the MOT sheet but not necessary to replace otherwise.

Recently fitted a replacement lower arm on wife's Juke and then replaced it a year later as the first (cheaper one) knocked the joint out in no time - more expensive one, quite a bit heavier duty for the N/S location and almost twice the weight. An easy job to carry out yourself and definitely not £1200 worth of repairs.

Kept the old rubbers to use if necessary in the future. :-)