Dear Nayna P
As I've written elsewhere, any advice I give can only be on the assumption that you have a reasonable panel. I cannot claim to read the mind of your particular IAP which operates outside of the local authority. (The chief adjudicator has just written in his report to the DCSF: "Aided and foundation schools should be persuaded to use appeals tribunals run by local authorities, diocese or private companies and should not attempt to negotiate the complexity of running their own tribunals.")
His response was that he is not really in favour of Grammar schools
I wouldn't set out to be too critical of the head, but you could mention this briefly to the panel, so that they understand what might lie behind his lack of enthusiasm!
level 5's in core subjects ( no gradings-is this a problem?).
If you mean sublevels (5a, 5b, 5c), then most heads don't go into such detail. Of course, if a head is willing to predict a 5a, it helps make your case stand out.
gets on well with peers and then a few sentences regarding ds sporting achievments (HT coaches the school football team).
Unlikely to be of the slightest help!
There is no mention of HT gradings for suitability for grammar school eg 1:1. Do all HT give this recommendation and is it essential for appeal?
No, this is the system used over the border in Bucks.
No specific mention about English ability although, attached there is an example of ds work Is this recommendation detailed enough?
Well, you want to emphasise ability in English to try and explain the VR score should have been better. Presumably you have other evidence, e.g. a level 3 for reading and writing at KS1, school reports which mention achievement in English, evidence of a high reading age?
We have no mitigating circumstances
It may not matter too much if you're only a mark short.
First and foremost, you have to convince the panel that the VR score was a blip. (Does your son have any other standardised VR scores that could be used in evidence?)
Secondly, you need to convince them that your reasons for needing a place at this particular grammar school outweigh any prejudice that would be caused if the school has to exceed its admission number. See the Q&As, section C.