BA has bassinets but not sure about any restrains incorporated. I have seen these full body harness like things that attache to the adults seat belt that can be used for lap children and could probably be used effectively in a bassinet too.

Another option (one that I have used) is to bring the infant car seat along and strap it in to the airplane seat next to you. It means paying a bit more but at least you are certain the baby won't go flying. Also, as noted above the bulkhead seats are not always available and even if you have confirmed your seat assignment unfortunately there is no guarantee these days that you will get that seat or that they will have a bassinet available when you actually show up to fly.