Its okay - don't panic!! Leave a form of identification with her - it can be anything from a utility bill to a credit card... not just a passport or licence... the Post Office are less stringent about I.D forms - just some general proof is all they need. Your OH can take that down with them and just explain you live together and that you're away. I have things collected on my behalf a lot and all they ask for is some I.D of the named person... Never fear!