//Large convoys of HGV's will likely be the first en masse deployments of fully autonomous fleets //
indeed - and probably phased, with vehicles on motorways being the first, as legislation already exists to prohibit certain classes of road user, and this can (will) be extended to include vehicles that do not have autonomous capability.
society will also need to decide whether the use of autonomous trucks will go hand-in-hand with an increase in allowable weight - such a move will bring large economic benefits for every commodity consumed in the UK, but at an environmental cost as this would kill freight on the railways forever.