If you are driving an english car your speedo may well be marked in miles per hour on the outside ring of the speedo and kilometers on the inner ring. Make sure you are familiar with your speedo. A mistake could mean an on the spot fine.
You must carry at all times; a warning triangle, a spare light bulb kit. a high visibilty jacket for each passenger. your passport, driving licence, valid insurance, vehicle inspection certificate (if applicable) and road tax.
It is recommended that you also carry a fire extinguisher and a first aid kit.