Question: I wanted to know what was the name of the episode where these cancerous creatures suck the bones out of you and turn you into a pile of mush - it was one of the first episodes I think.
Answer: I don't think this was a Doctor Who story. It sounds more like the 1966 film "Island of Terror" (although it did star Peter Cushing who played Dr Who in two Dalek movies around the same time).
Other mistake: The Brigadier says UNIT HQ is 'a Top Secret establishment'. It is, in fact, so secret that it has a large sign outside informing the world not only of its function, but also the name of the commanding officer.
The Doctor: This is a situation that requires tact and finesse. Fortunately, I am blessed with both.
Trivia: Such was the popularity of Doctor Who in Britain in the mid-1960s that even the Beatles wanted to make an appearance in the show. So a scene was written into "The Chase" to allow them to appear. The idea had been devised of including a scene on the Time and Space Visualiser depicting a Beatles fiftieth-anniversary concert in 2015, with the Fab Four dressed up as old men. John, Paul, George, and Ringo themselves were interested in the proposition, but it was vetoed by their manager, Brian Epstein. It was then thought that an appearance by the Beatles on Top of the Pops might be used instead, but no such footage was available. Fortunately, the Beatles were scheduled to perform "Ticket to Ride" at Riverside Studios in Hammersmith on April 10th, 1965, and that footage was used instead.
Answer: Your right it is, "Island of Terror."