A friend of mine is in a situation, where she has been living with her partner for over 20 years. The house and all the utilities are in his name and she just contributes towards food and other incidentals.
Over the last year, he has been continuously playing away with a number of much younger women and wants her to leave. She saw a solicitor, who said she may be able to make a claim on the property, but there was no guarantee she would get anything, even though she is financially dependent on him.
Cohabiting couples do not have the same rights as married ones, unless you live in Scotland. A bill was due to be introduced in England to give cohabiting couples the same rights as mariied ones a few years ago, but it never got off the ground.
So in a nutshell, your partner probably has very little right to your home, but to be on the safe side, you should seek some legal advice or speak to someone at your local CAB office.