Hi MrsF
In answer to your question about carers allowance, due to the fact you are not working now, you will only be entitled to the carers premium which is approx £29.50 (dont quote me as hav not worked for CAB for a while!!!)
This is because carers allowance is taken into account when calculationg your benefit and is classes as an income, this is where the prob is as claiming carers allowance takes you over the threshold for benefits which is why your only entitled to the premium when you not working, and is classed as an overlapping benefit and you will qualify as you have an underlying entitlement to it. This is if you get income support or JSA.
It does have a knock on effect on other benefits and tax credits you recieve, i assume you have already claimed child tax credits disability element.
Get yourself down to the CAB for a full benefits check as the info given on here is only a guideline and each circumstance is different.
Hope this helps
Juliexx
Sorry forgot to add, it wont have any effect on the amount of DLA your son recieves