Start by asking yourself whether you ever have any money left at the end of the month. If the answer is yes & it happens fairly often, then it is reasonable for at least that amount to be paid to the creditor.
Then - whether the answer is yes or no - you need to work out what you spend your money on. Some things you obviously put down - whatever you give your partner as a contribution to rent, utilities etc.; whatever you spend on food & other housekeeping items, including a sensible amount on alcohol; travel costs including everything you spend yourself on the car (finance cost, road tax, fuel, MoT, servicing, insurance if you pay them all); expenditure for your daughter including for her reasonable social life; all the other items mentioned in previous posts. This may end up with you not having any money available for the creditor, in which case you put forward a nominal payment offer - e.g. £1 per month.