"EastEnder's Game"

From imdb.com and Wiki:

In the near future, a hostile alien race led by Grant and Phil Mitchell attacks Albert Square, in East London and takes over the Queen Victoria pub.

The plot is built around the idea of relationships, strong families and the legendary heroics of International Fleet Commander Mazer Rackham, with each character having a place in the community.

In preparation for the next attack, the highly esteemed Colonel Hyrum Graff moulds the entire community into a family of sorts, prey to upsets and conflict, but pulling together in times of trouble, such as when there is the threat of annihilation by a technologically superior alien species.

The International Military are training only the best minds from Beale and Fowler families, consisting of Pauline Fowler, her husband Arthur Fowler and teenage daughter Michelle Fowler. Mark Fowler, a shy but strategically brilliant young leader, is recruited to join the élite.

Arriving at Battle School, Pauline's twin brother Pete Beale, his wife Kathy Beale and their teenage son Ian Beale quickly and easily master increasingly difficult challenges and simulations, winning respect amongst their peers for their full English breakfasts.

Mark Fowler is soon ordained by Graff as the military's next great hope, resulting in his promotion to running a stall in the market. Once there, he's trained by Mazer Rackham himself to lead his fellow stall holders into an epic battle with the Mitchells that will determine the future of Earth and save the human race, while Sanjay minds the stall.