1. With one in College + one in 2ndary school , you will need that k20 you have saved, if only as comfort until they are through college.
2. With AVC @ k25 it will help on short service.
3. k53 on tracker with only 8 years left , I would be tempted to keep it going , only pay off when rates increase (and they will).
After 8 years , you will have nil debt , your k20 intact and k25 AVC to bit fund shortfall.
And big pluses of girls through college and free home = yippee!