I am right in saying that they must give you notice of date and reason for meeting in writing if you request it aren't I?
Absolutely not true - elders are explicitly and repeatedly counseled to never put anything in writing!
The question is are you entitled to have a representative of your own at a judicial committee?
Depends on your friend's sex, age, and marital status (believe it or not).
A minor (under age 18) is entitled to have his parents there with him.
A married woman is entitled to have her husband with her, so long as he is a JW in good standing.
Anyone else (single woman aged 18 or more, any man aged 18 or more) is absolutely not permitted to have anyone else there with him/her, for "support" or any other reason. Any witnesses to whatever the JC is about will be invited in, asked to give their testimony, and then dismissed.
If your friend doesn't play by their rules (e.g., refusing to show up for the JC meeting, or insisting on someone being there for support), the elders will hold the meeting without him/her present and very probably decide to disfellowship him/her (having a "bad attitude" & not playing by their rules shows a non-repentent spirit, in the JW elder mindset).
If your friend does not wish to be DF'ed, the best course to take is to confess openly, weep profusely, and talk endlessly about his/her personal shame for "bringing reproach on Jehovah's name". That phrase is super-important - he/she should mention in at least a half dozen times during the JC.