For such an in depth financial taxation question you could try this website.
http://www.taxationweb.co.uk/
I have used it from time to time with good answers being provided.
I don't understand too much about trusts either. The Chancellor/HMRC don't like them in general because they can be used by the wealthy to shield income from tax. However there can be very good reasons why a child could have a trust fund established that are unrelated to tax avoidance - inheritance following death of a parent or as part of a divorce settlement, say.