Returning to work. What r my entitlements?

I've just been offered a fab part time long term temporary position, but the hours will be anything between 14 and 22 hrs per week. I'm a single mum and the hourly rate is above the minimum wage. For all the advice from the relevant agencies, i have no idea what i will be entitled to and this is a littlel worrying. Please, if anyone has actively returned to work in a similiar situation i'd appreciate some advice on what to expect. Any professionals/benefit advisors.. explain in 'pig-english' lol, thanx!!