(2-part post):
I assume that your mother was not married at the time of her death. If she was, unless her estate her very large, everything would normally automatically pass to her husband.
If you mother left a will, the executor can't distribute the estate until he has obtained probate. Nobody else has any rights to know the contents of the will until the will has been 'proved'. The will then becomes a public document, which anyone can read.
If your mother did not leave a will (and was not married when she died), any of her children can apply for a grant of letters of administration. (They then become an 'administrator', rather than an 'executor', of the estate). The administrator must distribute the estate according to fixed rules. (It's not a matter of 'doing the right thing by people'. There will be some people who're entitled to a certain proportion of the estate and others who may not be entitled to anything at all. The administrator has to follow the rules).
While a probate office can't reveal the contents of a will until it's been 'proved', they may well be able to tell you if an application for a grant of probate (or for letters of administration) has been made. You can find the contact details of the relevant probate office here:
http://www.hmcourts-service.gov.uk/HMCSCourtFi nder/
(Set the bottom field to show 'Probate court' and click 'Find court'. You'll be taken to the first of two pages of addresses).