Can I use my son's UK disability badge on his behalf?

Hello. My son has Tuberous sclerosis and acute Autism. Due to his condition it makes it very difficult to take him out for long periods as he is very difficult to control so i usally get my oldest to look after him at home while I go and get food shopping. The other week I needed to get his medicine so i left him with my oldest so i could go and get this. As he wasnt in the car i didnt think it right to use his disabled badge. But i found it very difficult to find a parking space and as a result i was almost gone for 2 hours and left my 18 year old alone with a difficult child and no help. It always scares me when i am not around to look after him for long times. So my question is. Can I use my sons badge to go and retrieve his medicine,due to the fact that he is unable to walk long distances and be left in the car? My son is 6 by the way.|||As he is a disabled minor and you are his legal guardian, there should not be any problems. They might ask for ID to show that you are indeed his parent, but that's about it.