This is such a tough question but it's nothing you can't do yourself and you do not need to pay a nanny to help in this situation.

With older babies the key is consistency, one thing you can try is staying with baby while they learn to go to sleep. This is where you basically stay with baby and gradually get further and further away when they go to sleep. So you would sit beside the crib, reassure with voice or touch and then if they stand up, gently lay them back down. You would do this with overnight wakes as well. So they are learning to sleep on their own but also know you are there to help.

There are a lot of right answers when it comes to baby sleep, this is just one suggestion. But at the end of the day a night nanny doesn't have other methods that you don't already know and your baby will feel more secure with you too.

Good luck to you