Okay, so let me see if I got the last two episodes right.

A spaceship crashes into Big Ben one year in the future. Only it's not a real space ship, it's a genetically modified pig who's been taught to crash into monuments by other aliens. The Prime Minister goes missing, and so partliment is replaced by fat people who fart a lot. These are the aliens who taught a pig how to be a kamikaze space boar. The aliens want to blow up the Earth so that they can sell it for starship fuel. As the aliens are killing a bunch of people, the Doctor, realising that their farts smell like bad breath, figures out that vinegar will make them explode. Meanwhile, Rose's boyfriend hacks into the Navy website, and uses it to launch a missile at 10 Downing Street. Rose, realising that door frames can withstand missile explosions, saves everyone who's important's life as the whole of 10 Downing Street explodes, killing all the aliens who've decided to gather there for some reason.

Okay.