complicated tax credits and redundancy

Hi everyone this is my first time posting. We are having a hard time working out whether to take voluntary redundancy pay or not. My hubby wants to change careers and potentially is entitled to 15k redundancy which would pay our debts off and give us 1 month to live before he had to get more paid work. Thing is we have 5 children and no other income so we rely on tax benefit s (up til now we rely on them due to debt but seen as we will be debt free that wont be the issue but whilst hubby gets a lower paid job we will need them to live) . Anyway, im really worried the redundancy will affect the credits, i know usually the first 30k is tax free so surely we should be fine to claim it but on the redundancy claim form only 10 or so is redundancy the other 5k is holidays and wages owed so if we get that in a lump sum will it up his annual income enough to affect them. If he is going to do it unfortunately it has to be now which is a shamr because if it was in a few months it would have passed april and be next years earnings which would be fine. Its so tempting as we could be looking at being debt free but we still need money to live and the safety net of tax credits.
Any help appreciated xx