Ready to leave nannying...

I need advice on how to give my family notice that I will be leaving. I have been with them for about two years, but am ready to take the next step in my life and find a career outside of nannying. When I took this position, the parents asked me to give them three weeks notice should I decide to leave. My issue right now is that I am currently looking for a new job, but have no idea how long it will take before I find something. It could be a week, and it could be a month. I am concerned that needing three weeks before starting a new position will hurt my chances of finding a new job. I don't want to miss out on a potentially great job just because I need to give my family three weeks notice. I would love to tell my family that I am looking now, but am afraid it will take me a while to find something new and that they will find a new nanny, and I will be out of a job completely, which I absolutely cannot afford. I need some guidance on how to handle this situation - I am completely stressed out! Thank you so much!

Need to Move on..

I have a tough problem. I have been with this family for four years. The employers and I are not close but have a very good pleasant relationship. I am very close to the two children and love them. I know they are very satisfied with me and have done many things to make sure I am happy here, but the truth is, I don't want to work as a nanny anymore. I want to go to work in my field and start accruing a 501K and I want to have coworkers and go to happy hour. As much as I know this, I know that telling the parents this is going to be very hard on the whole family. I am asking you parents and nannies what can I do to make this easier on them? What kind of notice should I give? Some have suggested I help them find a new nanny but if that does not work, I would feel responsible and more guilty? Speaking of guilt, how do you get past the guilt? It is very important to me to end things on a good note as I don't want to be completely out of the children's lives. Help.