Trivia: Producer Gerry Anderson provided the voice of Robert the Robot in this series.
Trivia: The characters of "Fireball XL5" frequently left the protection of their spacecraft and floated around in open space with no helmets or spacesuits whatsoever. Producer Gerry Anderson's lame explanation was that, in the year 2067, spacefarers used "oxygen pills" that not only kept them oxygenated but also protected them from vacuum, lethal radiation and temperature extremes (so they didn't need spacesuits). In reality, the "Fireball XL5" characters didn't wear spacesuits or helmets because costume changes meant literally ripping the previous costumes off the puppets and meticulously sewing on new costumes, which would have exceeded the show's production schedule and budget.
Answer: Been living in the UK, man and boy, for 70 years and "tootie" is not a word we have ever used. So why Gerry Anderson uses it is a complete mystery.