If I was awarded compensation for an accident, with the sum including many expenses I have had to lay out personally during the period of my trust deed, how much of the claim would my trustee be entitled to?
Welcome to the forum Saxon1872.
There is no single answer to the question as it depends very much on the unique circumstances of the situation. You'll need to work with your trustee to sort this out as they have some discretion and will want to understand all of the relevant facts.
If you have experienced additional out of pocket expenses as a result of the accident and can substantiate them I think you have a very strong argument that they should be covered by any compensation.
The same would be true for likely future expenses connected to the accident, for example if you needed the services of a physio while you recover.
Any surplus over and above this is likely to need to be paid into your trust deed to help repay your creditors.