hellitops - op was asking whether employers would consider a nanny who wasn't intending to bring their own child along.
To answer your question. There are jobs out there where the employer is happy for a nanny to bring their own child, but these tend to be jobs where they are finding it a bit difficult to get a nanny. This could be down to a number of reasons but the main ones seem to be;
before and after school care (so split shifts ie 7.30am - 8.45am then 3pm - 6pm) which doesn't appeal to a lot of nannies without children as the earnings are considerably lower, even if they are looking for a part time job most would prefer 30 hours over 3 days than 25-30 hours over 5 days.
limited childcare budget - would like a nanny but can't afford the going rate in the area, a nanny with own child is usually 25-30% cheaper.
they live in an area where there are fewer nannies so they broaden their search to include nannies with their own children.
There are of course employers who quite actively search for a nanny with their own child as they like the positives that it brings - company for their own child, that nanny has actual experience of being a parent, that nanny is likely to stay in a job for some time as the nanny will also want stability for their own child to name a few.
What I would say though is that such jobs are likely to go to nannies that have working experience with children (particularly as a sole charge nanny)before having their own child. Most would question why you want to be a nanny with your own child if you haven't done this sort of work before - they may wonder if your motivation is solely so that you can work but have your own child with you.