unfortunately there isn't enough information for us to do a benefit check for you here to see if there is any financial help you might be able to get. You can have a read through the benefits information at www.scope.org.uk/support/disabled-people/money/benefits-advice or call the Scope helpline on 0808 800 3332 and they will be able to give you then name of some local organisations who will be able to do a full check for you.
Given what you have said about your son being asked to leave
the UK I'm not sure we are equipped to advise you on this part of the forum. If
your son has issues regarding his right to reside in the UK, I would suggest
you follow this link immigration
Or if there is no issue regarding his residence in the UK you
might follow this link instead Government-Student-Support