There are a number of disabled parking bays that are spread across the Orange car park at ExCeL. They are 5.90m x 3.60m.Any vehicle displaying the disabled blue badge is still required to pay the car park charge of £25 for 24 hrs. The car parking map is shown here, and the London International Horse Show will be located at the West End of the venue. There are lifts from the under-venue car park to the Show itself.
You can find further information about driving to and parking at ExCeL here.