In order to have access to the funds (unless the estate was very small) the executor MUST obtain a grant of probate. Banks, etc, won't release the money until they're provided with a copy of the grant.
Once probate has been granted, all wills become public documents. Anyone can consult them.
If probate has not yet been granted you can apply for a 'standing search'. That remains in place for 6 months. If probate is granted during that time you will receive a copy of the grant (including a copy of the will). A standing search costs £6. (If probate isn't granted during the first 6 months, you can renew the search indefinitely, at a further cost of £6 for every 6 month period).
If probate has already been granted, you can apply for a general search (which also costs £6).
This page tells you everything you need to know about standing searches, with the information about general searches also to be found towards the foot of the page:
http://www.justice.go...standing-searches.htm
Chris