So I finally got around to installing the drops & brifters after a massive faff with the stem (which was resolved by using the existing mtb stem in the end, *sigh*)

I couldn't believe how easy it was. I connected the cables and with a small amount of adjustment, it works, front and back. Works really nicely too. The brakes on the other hand were a massive pita to get right, but that was down to the calipers as opposed to the levers.

If anyone's thinking of trying this, it's a lot of fun. The bike is a really good fun ride now. Thanks again to everyone who replied.