If a bank account is in trust for someone, like a child can a levy be put on that account

If the debtor is listed as a co-owner of the account it is subject to attachment. But if the account is held in trust then it belongs to the person who its in trust for.

Thanks for that answer. Here goes another, if the bank account is in only my name now I know they could freeze it, but if I add my sons name to the account, how should I do it so they can't touch it.

That won't do it. As long as you are a part owner of the account, its attachable. Unless you can prove all the funds in the account were your son's then that won't help.