Polarisation of L1 Data

Do anybody know why the most of S1 GRDH-Data are only available in VV polarisation?
Actual i need HH Polarisation, but only get results for V V (99%). May i still use V V, instead of HH ? Or is there a great difference in reflections-behaviour of sandy surface?

this is due to the observation scenarios of the Sentinel mission. VV is the standard polarisation and only a few test areas are covered by HH at the moment.
Have a look at the following maps to see which mode and polarization can be found at which places: