I've just found out that my house-sharer is actually the landlord - is this legal?

Does anyone have any idea if my rental agreement is valid? The name on my contract is her father, and that's who I thought was the owner/landlord. He signs everything and I pay the rent to him. I got a copy of the Land Registry and it turns out that my roomie is the real owner! She now tells me that as the landlord (herself) is living in the house, I have virtually no rights and am considered to be a lodger. If I'd known this in the first place, I'd never have rented it. She has now told me to leave by next month, presumably just because she's annoyed that I found out. Any suggestions?