(Second Part):
There are various problems, however, with running a national search using UK Info Disk. Firstly, since 60% of all phone users are ex-directory, there's a very good chance that your wife won't be listed in the phone directory. (Even if the phone number and address are listed, they might well be in the name of a new partner). Secondly, only the 'edited' electoral register is included in the UK Info Disk. If your wife put a 'X' in the 'Exclude from Edited Register' box on the electoral registration form, her name won't be listed. Lastly, unless your wife has a unique name, you will only get a list of people who share her name. (When I'm looking for people who don't mind being found, it's not too much of a problem to write to a hundred people to ask if they're the person I'm looking for - but all your wife would have to do would be to ignore the letter).
The only reliable source of information is the full electoral register but the only peope who can access this are the police, credit reference agencies, etc. Don't bother asking the police (or anyone else who has access to the full register). Anyone who gave you information would be subject to dismissal and imprisonment.
Your only real hope of contact is via your wife's relatives.
Chris