Irn Bru (Iron Brew) is Scotland's favourite fizzy soft-drink, but it's available all over the UK. You must have seen it in the shops, Frankie. It's actually available 'on draught' (ie. from the pumps) in Scottish pubs.
I've no idea how to describe it myself, so I lifted this from the website "British Delights":
Irn Bru is one-of-a-kind. Its orange color reminds the consumer of orange soda, but not exactly; it also possesses a sort of deep, zesty hue that recalls shades of rust, or wine. The initial smell is clean and cool, and vaguely reminiscent of tangerines.
Drinking Irn Bru is an experience unto itself. There's an initial rush of flavor, but of what sort is unclear; and then the distinct taste of water. Utilizing Scottish techniques that elude explanation, Irn Bru somehow manages to taste more watery than water itself.
The verdict is positive: Irn Bru is refreshing, oddly colored, and unique.
Personally, I recommend trying it!