I feel your pain. Duties on shoes here are 18%, and then there is 13% domestic tax on top of that. And when the package is sent by courier, it seems that they find every way to screw up an already bad situation to make it worse. I once got hit with ~ $190 customs bill on a ~$250 pair of Loakes. That crap never happens when I have stuff shipped by trackable post. Most often it comes through with no duties charged at all.
On the sizing issue, I contacted Meermin ant told them I had slightly wide feet with a moderately high instep and that I took a UK8.5 in Carmina Rain, but sized up to UK9 in Forest. They recommended I go with UK9 in Hiro. I was leaning that way in any event - if I'm going to miss, I'd rather the shoe be a little big than a little small.