Dear........Please accept this as formal notice of my resignation from the position of ....., with effect from.......
In accordance with my contract of employment I am happy to continue to work until ......
After being back from maternity leave, I have found it difficult to confidently comprimise my time between family life and work. Another opportunity has arisen to which I feel will meet my needs accordingly. I am sorry to leave, and I thank you for your support during my time with the company, which I have found enjoyable and fulfilling.
I would appreciate a further discussion to detail my personal situation in more depth.
Yours sincerely....
Ok, a bit rough around the edges, but somtehing to work on?