Having skim read each parties' manifestos to find any mention of SEN, i had missed any reference to it. I then e-mailed my local candidates and heard back from the lib dem candidate, who advised that on page 34 under "your life" it states that they will:
"Guarantee SEN diagnostic assessments for all 5 year olds, improve SEN provision and improve SEN training for all teachers".
He has acknowledged that this is only one line and doesn't explain how it will be done, but advised that there was a lot of detail that didn't make it into the manifesto as he knows some of the team who worked on these policy areas.
Not sure how the guarantee will apply to those of us with SEN children over the age of 5 that still haven't been assessed ( DD's now 8!) but at least there's some mention of the SEN system.