Good research pays off after all! I managed to find the "one size fits all" charger/connector for all my travel needs, which will save me a lot of precious pannier space:
the Kensington 70w AC/DC Notebook Power Adapter takes anything from 12 to 220v for input, and it comes with various adapters to fit various mobile devices such as mobile phones, iPods and laptops. Now, it doesn't come with a 'magsafe' MacBook connector – but fortunately, a guy called "Mike Gyver" modifies them. Thanks to eBay I found one used for a reasonable price.
