Possibly adopting in the UK

My husband and I have two children together and I also have a child from a previous relationship. We've been married for 5 years and live in the UK.

My girls are 6, 4 and 2 years old. We want another baby but we'd like to adopt rather than have another of our own.

Is there anyone here who's adopted a baby in the UK and can tell me how it went. Is it a long process or is it quite easy to "be found" by a birth mom? Is it expensive? Lost of legal fees etc?