Hi SP_
It depends.
You don't have to worry about AB, because we don't use OpenSSL
If you are a member of an affected wesbite, such as mumsnet, you should change your password AFTER they have said they've fixed it.
IF you use the same password on mumsnet as you do on AB then you should change both your Mumsnet and AB passwords AFTER they have said they've fixed the issue.
Heartbleed is like eavesdropping, and you can only be "listened to" if you're transmitting data, such as logging in.
If you haven't been notified by a company, it's unlikely they were effected. I would suggest changing your passwords after everything has "cooled down" :)