Hecticheron
It is worth you getting a second opinion, do an internet search for "welfare advice" with your postcode, town or county, but I think it likely that your son will be classed as a non-dependant adult living with you, as he is no longer in education and that will preclude you from receiving the Severe Disability Premium.
The requirements for SDP are;
- you receive DLA Medium or Higher rate Care, PIP Daily Living or AA
- you live alone
- no one is receiving Carers Allowance for you
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems