I answered someone else on a similar subject earlier. They were appealing against a completely negative decision on PIP, so slightly different. This is what I said:
“I haven’t gone through the appeal process, so really can’t advise you. But I would recommend joining https://www.benefitsandwork.co.uk/ They have excellent guides for members. It costs about £20 for a year, but it’s worth the money.
The only other thing I’d suggest is not to rush into appealing. Make sure you’ve absorbed the information about how to appeal, the points you feel you should have scored (check this by looking at the Activities and Descriptors on https://www.citizensadvice.org.uk/Global/Migrated_Documents/adviceguide/… ) and make sure you have sufficient evidence to support your claim. If you don’t have enough evidence, start the ball rolling on that ASAP.
Once you are really clear headed about your plan of action (you could also try to get help from the Citizens Advice Bureau), then appeal. Just make sure it’s within the month of the MR date.”
With regard to your specific question about taking someone with you, I imagine you are talking about someone representing you. This could be an advisor from the CAB, or another welfare rights organisation. It could be a solicitor, but you’d have to pay for that kind of representation, and of course you’d have to find a solicitor expert in PIP as well. If you don’t have an expert representing you at the appeal (of course some appeals are decided on without a physical appeal hearing - generally just the appeals decided in the claimants favour and as you were only one point shy of the maximum that could be you), then it helps just to have someone with you - in terms of moral support.
Best of luck.