asking my mum for birth control

me and my bf have been sexually active for just over a month now and we always use condoms but I'm still scared in case something goes wrong and I really don't want to end up pregnant so I'm going to ask my mum to take me to the doctors to get on birth control but I don't know exactly how to ask her. I know she'll be pleased I could speak to her about this and she'll be glad I'm being responsible but I just don't know how to bring it up. any advice on how to start this conversation?