UK Branch

We have recently been approached by a UK based (and registered) branch of a Netherlands parent company (which in turn has a US parent compeny). We need answers to the following (and can't get a straight forward response from Companies House) -
Whose accounts need to be filed in the UK?
If it is the holding co's, do they need to be in sterling?
Is there a filing deadline?
Is there a problem if the year ends are not co-terminous?
Any comments/experiences would be gratefully received.
Vickie Nobbs