Hi KM31,
Your banks use Experian and Equifax as the main credit reference agencies.
There is a website called Creditexpert that is run by experian, which you can use to get your report, or subscribe to to get updates on activity on your credit record. I think I pay 6.99 per month for this.
This will give you a summary of the amount of credit that you have access to (outside mortgages).
It will also showed Linked addresses and linked persons where you had obtained credit at different addressess, and who you may have applied jointly for credit with.
It is worth checking these carefully as I had some erroneous linked addresses and multiple versions of the same address.
You can ask to have these removed, which experian will go back to the credit company (bank) and confirm.
Good luck.
Sparky.