I would suggest sleeping in the same room as the baby when he arrives for a while. Hear his noises and get up and basically train yourself
I think it's a mommy thing. I was a super hard sleeper then I had my son (7 years ago) since the day he was born I became a light enough sleeper to hear the smallest peep from my little guy.
Since I was a kid I've been a hard sleeper. My mother use to say I could sleep through a tornado. I'll sleep straight through an alarm clock but a baby makes a peep I hear it. I think it's instincts. I'm sure you'll be fine!
I think that your instincts will kick in and help. Sometimes with my first I had a hard time getting myself up, but I wouldn't worry :-)