Do you have a statement for SEN? If you do, you **might** be able to get some allowances during the test (my son got a smaller test room, but no extra time).
Also, if you name the school on the statement (providing your child passes) they have to be offered a place, no matter how far away you live. Although it will probably be your responsibility to get them there every day.
If you don't have a statement there will be no special allowances - or so I was told.
I'm going through it at the moment