We have a special needs son and looking at setting up a will and also a trust to look after his needs when we are gone. Just wondering if anyone would have done something like this and have any idea of what would be the likely costs?
I don't know specifically.
Charges in these matters depend on the amount of work to be done and the degree of complexity.
Your best option is to shop around a few solicitors.
Describe briefly what you want done and get from the solicitor an estimate as well as a summary of the work required before you engage them.
In fact, you should ask any solicitor you approach to provide you with a S. 68 letter.
Link to the Law Society's do's and don'ts page on the subject