There are two options - you can walk across the bridge itself or there are the locks that you can walk across which then takes you under the bridge, this avoids having to cross the busy road at that time and would be the 'safer' route and it brings you directly to the front of the hotel.

To get to the locks come out of the garden walking towards the bridge, turn left at the road that leads to a small parking lot area. Keep walking straight and go across the locks - there will probably be a lot of people doing this. Walk along the right side of the park and under the bridge, the hotel will be in your right. A link is below that shows where the locks generally start.

If your coming from the hotel to the garden this is also a great way to get to the concert.

Lovejoy Wharf