Hello! It wasn't that expensive really. It was around £65 for the shifters off
ebay. I got 8 speed ones even though mine is a 7 speed bike (like yours). Both work. I think it needs to be Shimano Sora as those are the only 7/8 shifters around (correct me if I'm wrong). It was certainly tricky to convert but I managed to do it even though I've never done anything remotely similar before. It's nice to know I can do all the maintenance etc now though. Then it was £2 for gear cable housing! Spent some money on new tools as well but you might have them already.
I've got to do it all over again now (to a certain extent) with the new handlebars when I get them.
Pete, I saw those randonneur bars and like them, I really want to find a picture of how they look actually on the bike but can't seem to find one. I'll keep googling!