logging in was the problem here. I used to book many helsinki-uk flights using lh.co.uk without login. I think at some point they asked for an address in the Uk but gave a family address there. Nothing was posted there anyway. I even used discount vouchers issued by lh uk (eg 20 pounds off a booking). Now it's all changed and i'm charged in euros regardless of login or not.

At least the exchange rate lh use is a resonable one. Sites like amazon and play.com will offer (or make it compulsory) to pay in euros for non UK customers but use a non optimal exchange rate (in play.com's case about 10-15% surcharge for paying in euros).