The Surface Pro 4 type cover with a Fingerprint Reader was only available in USA until recently, and when it arrived in Europe it debuted at the rather high price of 179 Euro.
If that has been putting you off however Amazon Germany now has a great deal on the accessory, offering it for only 139.98 Euro (£110). The company ships around Europe, including UK.
The accessory brings Windows Hello support to the Surface Pro 3 and augments the face-reading Windows Hello on the Surface Pro 4, and is generally considered to be more reliable than the other technology.
The accessory can be found at Amazon Germany here.