Doctor Who: The Visitation (1982) written by Eric Saward and directed by Peter Moffatt
Fifth Doctor Peter Davison tries to return his companion Tegan (Janet Fielding) to Heathrow Airport in 1981, ending her adventures with him. The TARDIS gets the location right but the year wrong. The year is 1666 and the plague is raging throughout England. If that wasn't bad enough, a "comet" crashed recently which the locals took as a sign of doom. They are quite right of course, because it was actually a spaceship. The Doctor wants to help the stranded aliens get back to their home world. Those aliens, the Terileptils, have other plans, the typical enslaving and/or wiping out humanity so they can have the Earth to themselves.
The show has the usual antics--kidnappings and escapes, chasing good guys or bad guys, building a science-y weapon, bantering between the Doctor and the companions (two others are on board in addition to Tegan). A fun addition is Richard Mace (Michael Robbins), a highwayman who used to be an actor before the plague made theater-going less appealing. He helps out the Doctor with his highwayman skills (picking locks and shooting pistols, that kind of thing) and provides some extra comic relief. The aliens are typical Doctor Who baddies, though at least they are imaginative enough to dress up their android as Death to scare the locals away.
Overall, this four-parter is a fun if a bit average adventure for the Doctor.
A bit of fun trivia--in the special features, they mention that Peter Davison played Tristan in All Creatures Great and Small, which made me look at his career on IMDB. Another fun role was this one:
I laughed because I knew exactly what role he had just from the name! He's the cow that points out his best parts to diners at the Restaurant at the End of the Universe.