We have the same taps in our bathrooms.
To take off the tap heads: You need to unscrew the top domed cap - but it is not easy to do!
Then you can get to the screw beneath and by unscrewing it you can remove the tap head.
It is really difficult to unscrew it though - we are trying to unscrew our taps to change the washers, but no luck so far.
CH
May 2010