Patient HTC One owners in Europe should finally be getting their Lollipop updates any moment now. The OS will still be running HTC's Sense 6 skin, so the change won't be quite so drastic as it is on AOSP ROMs. The download will be 804.8MB, so be prepared for the necessary space and time to download.
The new ROM version is 7.19.401.2. Several people from across Europe have already received the update, so you may want to manually check if you haven't been prompted yet. No significant problems have come up yet, so you should be in the clear in terms of avoiding crippling bugs and things like that.