Firstly take a look at the following link with regard to diability and the 11 plus. Have you applied for extra time?http://www.buckscc.gov.uk/assets/conten ... _Entry.pdf
In respect of tests, is your tutor actually teaching your son method and techniques or just "babysitting" whilst tests take place?
AFN and IPS are easier than the real tests. Susan Daughtrey [Bright Sparks] are of a similar standard to the official tests. The first few scores for Daughtrey are reasonably acceptable, I always aim for 90%. What order have they been completed in as each pack is graded, therefore 4 and 8 are the hardest, with 1 and 5 being the easiest.
Codes and some maths will take longer to complete, therefore I tell children not to panic, however there are specific Method and Techniques to help. [something your tutor should be covering] It is encouraging to see Vocabulary and Maths are his strenghs as Vocabulary is the biggest problem.
I understand children with Asperger's syndrome need structure, so an hour a day of parental help may be appropriate. [would not be recommending such a regime for children who do not need extra help]
What other tests do you have, what else has been completed?
Mock tests at this stage would only be beneficial if he has mastered all techniques, otherwise it mat be demoralising.