Have a look at paragraph 9.69 of the Code of Practice.
Section B should contain a reasonably detailed and complete description of your son's difficulties so that people working with him know what to expect. It's not good enough, for instance, just to say he has literacy difficulties: if that is the case, it should say whether those are in relation to reading, spelling, writing, comprehension etc, and possibly how far behind his reading/writing etc ages are. If it lists strengths, check whether they really are strengths.
Sections C and D should have quite detailed descriptions of education-related health and social care difficulties.
Section E should have sensible outcomes that reflect the benefit or difference everyone is hoping will be the result of the provision in sections F, G and H. They should be SMART and should cover a range of timescales. They should also ideally relate to each main area of your child's difficulties.
Section F should contain provision to meet each of your child's needs, and that provision must be detailed and specific. Look out for vague wording like "would benefit from", "regular", "as appropriate", "up to", "access to" etc and challenge it. Likewise with support to come from unspecified "adults": if your child needs 1:1 support, the Plan needs to specify that that person is dedicated to your child, i.e. can't be nicked to support others - assuming, of course, that that is what he needs. Programmes should set who is to draw them up and supervise them, and who should deliver them (e.g. TA, teacher etc).
G and H again should be reasonably detailed and specific descriptions of health and social care provision related to education.
I will have been left blank because it is for you to say what your preference is in terms of schools.
I found SOS SEN's booklets really helpful - www.sossen.org/shop/index.php?cPath=22