There was a radio drama? I'm intrigued now, is it available anywhere? Britain doesn't tend to import radio programs.
But back to the original question:
Number 1, I'm an old-school-day 1 fan, I started reading them in '97 (when they were first available in the UK). Every year my school had a book fair and my parents always pressured me into buying at least 1 book. The Invasion look interesting so I got it and was completely hooked. I read most of the book in one sitting, which was completely unheard of for me back then.