I’m getting by with one plug adapter for a fairly extensive array of electronics. I have two cameras with two backup batteries each, an iPhone, an iPad with keyboard, a MacBook Air, a Kindle, and a backup USB battery. With one adapter each of these has to be charged in turn. The exceptions are the iPhone, the Kindle and the iPad keyboard, which can be plugged into either the backup USB battery or the Macbook while they are charging.
It takes a bit of forethought to decide what to charge when. If I were less stingy I’d probably just spend £6 on another adapter, but that would be too easy.
An interesting thing about England is that every outlet has a switch. In fact there’s even a switch specifically for the stove in the kitchen that you have to remember to turn on before you try to use it.