Can anyone tell me/advise if you get banned form driving a road vehicle for drink driving should you/are you also banned form driving plant on site? Would it be considered best practice to also be banned from plant vehicles?

Lets reverse your question - if someone does not hold a full UK (or equivalent) driving licence does that exclude them from operating plant or driving FLT on private premises? The only manner I can think of that a drink drive ban would directly impact an employee driving "for/at work" is if their contract had a specific clause regarding loss of their Road Licence resulting in dismissal - but this is not the same sanction as keeping them off the vehicle whilst remaining employed. If this was the result of a history of alcohol abuse your policy should have already kicked in long before any court appearance.

Good Points, thank you very much, but another point I did not consider is, if you are working in the public domain, using a digger on a public road would the ban be enforced as you are driving a vehicle on a public road?

The Road Traffic Act applies to vehicles used in any "public place" but unhelpfully, this is not defined in the act and each circumstance will need to be considered on its own merits. If the vehicle is used anywhere where members of the public could feasibly be injured by the vehicle, it is likely to be subject to the RTA so the banned driver cannot use it. For those interested in insurance law, Mr Vnuk was knocked of his ladder by a tractor whilst working on a farm in Slovenia, and the European Court of Justice held that the requirement for compulsory insurance applies to private as well as public places. As we are (currently) bound by EU law, our own law will need to be extended to include compulsory insurance for vehicles used on private land. The UK Govt is allowed to exclude certain classes of vehicles from the requirement, but at this stage, nobody knows how it will be enacted. Speaking from the perspective of an injured party, if you get knocked over on a site or on the access road to the site, should the requirement for insurance (and thus) the availability of compensation to you be any different?

Congratulations to the insurance industry - once again their penny pinching will affect the wider population. A search proved very interesting reading especially when this case was decided at the end of 2014. Would certainly impact any wide spread application of self driving vehicles (who is competently in control of the vehicle?). Given the government push on driverless cars and the need to rewrite the Road Traffic Act may explain why this case is not so widely known. Referendum soon - another example of why to leave? The topic has prompted a lot of discussion on motor sport blogs and potential consequences for go-karts, mobility scooters, farmers as only powered vehicles running on tracks seem to be exempt.