Birth Fears

All the way through my pregnancy I've been looking forward to the birth in a way. But I've been reading up on births and a lot of people have questioned our birth plan- but I have 5 weeks to go now and I'm beginning to have a lot of fears about the birth. I have anxiety and I'm afraid that I'll just have an anxiety attack under the pressure. 
Does anyone have any ideas on ways to calm myself or alleviate fears of child birth and all the uncertainties that come with it?