thats why I'd suggest phoning the regional animal health office (only when you've plenty of time free... we're in Derbyshire, been using Stafford office, then when I rang the other day they said you're under Leicester! So be warned... but we've always found them much more helpful than reading defra's rulebook!)
I'm inclined to think you'll need two separate trips, and disinfect the trailer in between, but don't take my word for it