just make sure you surround yourself with people who believe in your ability to deliver your babies vaginally. DOn't listen to all the people who try to scare you and don't let them bully you into an early induction/section.

I can recommend 'Double Trouble' is you're after some positive, pro-natural twin delivery reading.

My first was born at 40 weeks +1 day and I had a spontaneous vaginal delivery with my twins at 37weeks + 3days so your twins may cone earlier anyway.