Hi shezza
If your daughter is placed in the LCWRA group then she would get an addition element added to her UC of £354.28 pcm.
In answer to 'would she get any back money' it would depend on how long it has taken for your daughter to be awarded LCWRA. When you first apply for WCA the assessment period starts from when you give your workcoach a 'Fit Note' . You are eligible for payment from the 14th week of being in the assessment, but it can take many months after the assessment period before a payment is made.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
