In the Department for Transport guidance here,
http://www.dft.gov.uk/pgr/freight/road/working time/rdtransportworkingtimeguidance?page=4#a10 08 it says
"2.2 What is working time?
The Regulations define working time as the time from the beginning of work, during which the mobile worker is at the workstation (typically this means the driver's cab - but see glossary for fuller definition of this and other terms) at the disposal of the employer and exercising his functions or activities - that is to say:
(a) the time devoted to all road transport activities including:-
driving;
loading/unloading;
training that is part of normal work and is part of the commercial operation;
assisting passengers boarding/disembarking from vehicle;
cleaning, maintenance of vehicle;
work intended to ensure safety of vehicle and its cargo and passengers (e.g. monitoring loading and unloading - including daily defect check and report);
administrative formalities or work linked to legal or regulatory obligations directly linked to the specific transport operations under way.
If you look here
http://www.dft.gov.uk/pgr/freight/road/working time/rdtransportworkingtimeguidance?page=7#a10 31
it shows examples of work/rest and how European and UK law apply.