First I thought that I would look at Australian Standards:
AS2870-1996 the Australian Standard for Residential Slabs and Footings - Construction states in Appendix B, clause B2.3 (c) Restrictions on tress and shrubs:
"Planting of tress should be avoided near the foundation of a house or neighbouring house on reactive sites as they can cause damage due to drying of the clay at substantial distances. To reduce, but not eliminate, the possibility of damage, tree planting should be restricted to a distance from the house of:
1.5 x mature height for Class E sites.
1 x mature height for Class H sites.
0.75 x mature height for Class M sites.
Our soil report said that we had an M class site so I will need to push back to get a shorter area of protection.
I then did some more googling and I have since found that there is not a lot known about the direct effect of tree roots on foundations. It looks like the best option is to either obey the above in both your design and future planting of trees and then to get the advice of an arborist.
I think the best course of action is to put a root barrier in under the instruction of an arborist.