You may wish to inquire about dyspraxia; my son has had great difficulties with coordination and has greatly benefitted from occupational therapy. I understand that the research in the UK is more advanced on dyspraxia than it is here in the US.
I agree dyspraxia and/or Asperger's sound like possibilities, but the OP says she has reason to think she's under investigation for
MSBP. With that as a serious concern I frankly think she should stay out of trying to get anything diagnosed, and should stick to repeatedly reminding the school that her son needs to learn to write, and asking what they're doing about that and what she can do to support them. If there is a diagnosable problem that really needs to be diagnosed, they should get there eventually. It's not ideal, but ukmum, your son needs a mother who's not under attack more than he needs the perfect diagnosis and therapy.
As a start, here are a few suggestions for supporting writing. Think about whether he sees you writing! In our household an issue is that he probably does more handwriting in a week than either parent, given how computer-oriented our lives are these days. We haven't managed to "fix" this but at least being aware of the disparity helps. Handwrite little notes to him. Handwrite a shopping list and get him to help - maybe bribe him by promising to buy a small thing he likes if he writes it on the shopping list. Institute a 5 minute timed handwriting practice, daily or just at the weekend, in which you e.g. challenge him to see how many times he can write "cat" neatly. Give him sticky labels and some old takeaway boxes or similar and let him make labelled boxes for his toys. Basically take advantage of any occasion when he might see some advantage in writing, even if it's only a few letters at a time. Try different kinds of pencil and pen - maybe try those big triangular pencil grips, which make pencils more comfortable for some children, or try a thick marker pen.
