Worried about how to manage financially

[Amitolamummy]

I have been in a lucky position with housing and finances since I split from my sons father last year, but we need to move into rented accommodation very soon. I am on income support and don't receive much maintenance. My sons have several food allergies which makes my food bills much higher than normal. It looks like I will need to find £100 a month to top up the housing benefit I will be entitled too, in order to find a house close enough to my sons school. From September I hope to start working part time as my youngest can start nursery, but have no idea how long it will take me to find a job.
I'm really worried about paying all the bills, keeping my car (if I let it go i'm not sure i'll ever be able to afford the initial outlay again, plus it limits my employment options)
Is £100 rent top up ridiculous? Does anyone else have to find that sort of money each month? I've been treating myself a bit this last year, whilst saving some money too, because I know I will be watching every penny. I'm not sleeping anymore because I am so worried. I don't have any family or anyone to fall back on

I have a mortgage so only get mortgage interest help not housing benefit and I have to find £350 a month on top to pay my mortgage, its just about possible so I think £100 rent top up will be doable for you as long as you're organised about your finances.

Good luck with it because it will be stressful to begin with.

Thanks, that is a lot of money to find and would be completely impossible with the amount I get. I still can't see how I will find £100 and manage to pay all the bills, buy food, school uniform, lunches, trips etc. All those presents to buy for parties too. I guess I could just hope everything falls into place and I do find a job that improves my finances.
I never used to be this worried about things but I've been a sahm for a few years now and am completely out of practice with job hunting and things