This is famously the first published Doctor Who story in print of any kind.
It is an adapted novelization of the B.B.C. television serial "The Daleks" which was the 2nd serial of the 1st season of "Doctor Who" broadcast between 21 December 1963 and 1 February 1964.
This is a loose adaption with significant plot and character differences throughout.
The start of the book includes scenes where the main characters meet up, which was actually in the TV serial "An Unearthly Child" (the 1st serial of the 1st season of "Doctor Who" broadcast between 23 November 1963 and 14 December 1963).
As the author, David Whitaker (who was also the script editor for the 1st season of "Doctor Who") did not have the rights to the content of "An Unearthly Child" the scenes had to be completely rewritten.
The narrative is entirely from the point of view of the character Ian Chesterton, unlike the TV serials.