Circa 10,000 British troops were killed in action in the Battle of France.

http://en.wikipedia.org/wiki/Battle_of_France

Perhaps as many as 4,000 of these were killed when German aircraft sunk the liner "Lancastria" which was evacuating British troops during "Operation Ariel", which was the evacuation from Normandy and Brittany, subsequent to the more famous evacuation from Dunkirk.

A further 58,000 British troops were wounded or captured during the Battle of France.

The British also lost 64,000 vehicles, 2,500 guns, 931 aircraft (and a further 1,500 aircrew casualties), and 243 ships.

About 198,000 British troops and 140,000 French were evacuated from Dunkirk in "Operation Dynamo". The later evacuation, "Operation Ariel", evacuated another 200,000 British and Allied personnel.