Oh another Aussie opinion
I have a TB as well and struggle with his weight but I think I have finaly gotten on top of it :)
He gets 2 hard feeds a day, which consist of shandy chaff(mix of lucene and wheaten), Sunflower seeds, ACV and Equinm(a vitiam supplement designed for WA soils)
He also gets hay 1-2 times a day which is 2 of meadow and 1 of lucene.
If he gets hay once a day I turn him out for the day into a big paddock which has grass