Accessing your Police Record
This is an easy question to answer - if you are (like me) working in some country (Korea) where a criminal record is required (and I have had to do this twice since regulations changed in 2007), the procedure is to go to your local police force's web site and get the "Subject Access" application form, fill it in as required and submit it with a ten pound cheque; takes about six to eight weeks and you get a full record (assuming one exists) printed out. Ideally, with the addresses you give when you fill it in, there should be no criminal convictions against you, and it should state this explicitly.
Note that only _criminal convictions_ will be listed (if present) - things like County Court Judgements and minor misdemeanours should not raise a flag because they are "civil", not "criminal".
You should find that your local police web site has a download page including instructions on how to complete the form. This is forwarded to the National Criminal Database at the Met in London for processing.
Korea changed the E-2 visa regs shortly after the current President was elected in December 2007, and all applicants for an E-2 teaching job (i.e. in schools) are now required to do this in addition to undergoing regular annual health checks. You may also find that some additional verification such as an apostille or other notarisation is also required before it is acceptable (if you are going into ESL/TEFL, for example).
Finally, if you need another copy later, you should find that the local police are happy to just print out another hard copy as long as your details have not changed since you applied - otherwise, you need to put the new information on the application form and go through the process again.
IANAL and YMMV but if you want to, send me an e-mail if you have questions related to this.
Biting the hand that feeds IT
