I've done this 20+ times. Dived many times with Blue Ribbon - they are a GREAT operation, have fun
Ask Jon/Chris/Marcus (the instructors) in Blue Ribbon about travel back to Manila airport. They do it regularly & will give the best up-to-date advice.
I stay in Red Planet Makati (use the App to book, cheaper)
Red Planet Hotels
Or
Hotel Durban (has a great Italian restaurant & good wine)
Hotel Durban – A True Boutique Hotel in Makati
Allow 1 hour to get to airport. Use Grab (App - use GrabCar choice, not GrabTaxi). 2 hours during rush-hour.
I never change money at Manila airport - VERY poor currency rate.
Getting there that day:
No problem, take the 09:15 or 10:30 banka from Sabang to Batangas.
Then PUBLIC bus - ask for Makati or airport.
NB you might have to wait up to an hour for the bus to go, or take the Si-Kat (09:15) which goes straight-away.
I used to always take the Si-Kat but the public buses are now much more comfortable, MUCH cheaper (Si-Kat is 3 times the price), play a movie, and most have good toilets.
If you miss the 09:15 or 10:30 you should be fine catching the 13:30 - but beware - if that boat is cancelled, you'll have to take a private boat (3,500pesos).
NB during high season there is often an 11:30 from Sabang to Batangas - but it only runs if they are busy. I wouldn't trust advertised times by FSL!
Personally I would do an extra days diving, stay in Sabang, not Manila the night before your flight and take the 10:30 banka from Sabang to Batangas. Go to the casino (very near to the airport) to kill a couple of hours time in the afternoon before going to the airport (can leave luggage with the desk). Use Grab to get a taxi after you get off the bus to go to hotel/casino.
Hope that helps!