I'm pregnant and in a terrible dilemma, please advise me

I am 21years old and 13 weeks pregnant, I rent a house privately on my own and receive £172 p/m in housing benefit due to a low income. I work part time for my step father (between 12-16 hours a week), however, my mother and step father have just split up, due to him having an affair. I am in such an awkward situation due to working with him. I feel really stressed and now hate going to work with him; however, I know I will not find another job now due to being pregnant. I don't know what to do? If I quit my job will I be entitled to any benefits until I have the baby? And will I still be entitled to any maternity pay? I really need some advice as this situation is terrible. I feel sick with nerves everyday coming to work and I know I cannot take maternity leave until 11 weeks before the baby is born, which is not until the middle of August. The baby is due on 01/11/10. I would really appreciate it if someone could get back to me asap. Many thanks.