Kath
Requesting an appeal is relatively simple and only requires you to complete a form and provide some basic reasons for your appeal. It is certainly something that could be completed at your CAB meeting and then posted.
Once your appeal is accepted the DWP will prepare their submission to the hearing and send you a copy, whilst you should wait until you receive this to finish and submit your own, you should start to prepare your own case, an increased award will only be made by your showing that you score the extra points for one, so I would start by going back through your PIP2, the assessment report and the PIP Claim guide to see how you might show this is the case.
If you want to look at the form then the PIP Appeal guide has links to the SSCS1 form that you will need to complete and the Submissions guide has a complete example that you can use to help you fill it in, you do not need to provide detailed reasons at this stage for your request.
www.benefitsandwork.co.uk/help-for-claimants/pip Gordon