Hi Exmouth,
Were you able to get hold of your Mum's birth certificate and did it give you the information you wanted? It sounds such a lovely idea and I do hope you find out where she was born.
Incidentally I have sent you a pm with links to the probate records - there were quite a few death, marriage and birth records attached to those. To see your personal message just click on My Messages in the brown banner at the top of the page.
Ros