Babysitter wanted for childcare in London

Hi, we are a family of 4 with 2 young children. A 3 year old girl who is kind, energetic and playful and a 6 month old boy who is a cute as can be. I work in a seasonally demanding field and should need occasional assistance from the months of April to June each year. I would need help primarily from 4 pm to 8/9 pm 1 to 2 weeks a month due to my husband's shift work.