I agree that the Rommel book is worth getting. Forget the Lorraine setting and move it to Flanders, switch the French for Brits and Bob's your uncle (you'll have to get your own fog machine, though, they don't include one with the book).
Unfortunately there are no cavalry actions in that book.
I'll have a think while I'm at work. But for now how's this:
I read of an incident in a book about 1st Ypres that was quite amusing. A British officer and his troops were resting in a Belgian or French village. The officer was sat outside a delightful cafe enjoying a cup of tea and some food, while his men took the weight off their feet in the street after days of hard marching. At this point they saw a force of German cavalry appear at the other end of town who proceeded to dismount and then advance up the street firing their weapons.
The officer was of the old school, and understood how the army worked. He knew full-well that the NCOs were the real ones who commanded his men. His job was to inspire them by example. He must display unflappable bravery to the point of stupidity. So he decided to calmly sit there and finish his tea and croissants, while the Germans advanced up the street at him and bullets pinged past his ears. Once done, he calmly paid the bill and then ordered his men to retreat, as there were overwhelming numbers of the enemy.
So for the scenario you could say that the Brits must hold out until their officer has finished his breakfast (a fixed or random time, roll a die, draw a card or something), and then retreat with as many men as they can off their table edge. No retreating is allowed until the bill has been paid. Then everyone scarpers like hell.