get as much riding in now as you can....your opportunity for this will decrease as soon as the little one arrives.
as for sleep....get as much you can now as again there will be little chance of that happening once the little one arrives.
you're bound to have moments of fear especially if this is your first...that happens to all parents at some point, but worry not as it will disappear once the baby is born.
it happened to me twice and i'm sure it will happen again before our number 3 arrives in May.
good luck and hope all goes well.