Based on the highly popular BBC Children's sci-fi series which at the time of this film's release had only been made in black & white so this technicolor film was therefore a big hit with it's fans. William Hartnell, the then TV Doctor, was disappointed not to be given the role for the film which went to Peter Cushing who was more well known for US audiences. As fans will know the later TV scripts for the series have the Doctor as a time travelling alien but in the original and first series and this film he's a sort of bumbling Edwardian inventor who has cobbled together his time machine, called TARDIS. On TV he's always referred to as just The Doctor but in this screen version he is actually called Dr Who, which does jar a little if you have been bought up watching the series. That aside here we have Roy Castle playing the hapless boyfriend Ian of the Doctor's granddaughter, Barbara (Jennie Linden). He's the comedy element of the film and whilst being given a tour of the TARDIS he trips on the controls sending them all, including younger granddaughter Susan (Roberta Tovey), off to a desolate planet where they have to help peaceful Ziggy Stardust lookalike humanoids deal with the evil metal encased Daleks. The budget was clearly small and the sets are all tissue paper and string and the story has holes galore but this is clearly designed for children with much of the action and horror elements toned down to please the censor. It's all good fun and worth seeking out if you're a fan of the newer TV incarnations of the Doctor. It's recently been restored for BluRay and 4k UHD so is available if you have fond memories and want a a little nostalgia for your early years remembering how much the Daleks were very scary at the time.
This film has very little to do with the original BBC TV series. The Doctor (in this story he is called "Doctor Who"), is basically an eccentric inventor who has invented the TARDIS (not a wanderer in time and space who has stolen one), and if you are looking to catch up on some classic episodes, or introduce yourself to them, this is not for you (I think the original episodes can be found on the dual feature Doctor Who: The Monsters Collection: The Daleks which was released circa 2013. Go for that, it's much more iconic).