DLA tribunal interpreter?

I have just put in an appeal (via a local benefits advice service) for DLA, after having my claim for higher rate mobility turned down. I gather the appeal won't be heard until Xmas or the new year.

Unfortunately my health is in rapid decline at the moment. I have severe M.E, which makes both light and sound very painful - this means I wear an eyemask and earplugs all the time. Because I cannot talk above a whisper and cannot hear any reply, I now use deafblind finger spelling to communicate. This takes a long time, however! I know I will have to go to the tribunal and answer questions, but doing this by hearing and speech would be impossibly painful. Can I ask for a deafblind translator, or take a friend to translate for me?

Thank you for this website, by the way. It's a vital resource in a crazy system!