oh or can/would you store some of your luggage at the airport - there are lockers in between terminal 1 and 2...

a cheaper way to get into town is by taking bus A11.
the walking option: there's a stop at the wrong end of Percival street/Hennessey Road Fire Station if you look at a map. If you arrive late enough (post 11... which isnt too hard if you need maybe 30-45 min to clear customs AND retrieve bags and wait for bus, and another 60-70 mins for the ride), the 15min walk will be easy with no stairs to maneuvoeur.
the taxi option: if you get off the bus at Jardine's House (4th stop after all the highway/tunnel), there are usually taxis readily available to go wherever on your request. 15 minute max(50HKD) to the CP!

Or Airport Express+taxi is the most sensible (but cost 50HKD more than the bus+taxi option... since Jardine House and the train station are just opposite each other)