Must admit I’m not a big fan of citizens advice as they we’re as helpful as a chocolate fireguard when I asked for help when I lost my higher rate PIP.
That said they did give me the address of local council / lottery funded volunteers who were first class and I know they had specialist in money and benefit claims.
Might be worth asking your council office or your local councillor if they know of such persons, south Bristol here so not worth giving the address of the folk who helped me unless your in these parts.