I'm trying to pay money into an account. I have the Sort Code and Account Number, but no account name. I know the company that owns the account, but I'm sure they have MANY accounts. Can I put just put "XYZ company" as the account name?
To the best of my knowledge the UK's online banking systems look purely at the Sort Code and Account Number when routing transfers. The name is not cross-checked to ensure it matches. This is why it's so easy to misdirect transfers if you make an error entering the numbers and inadvertently enter the details for a valid account belonging to the wrong person.
So in your case so long as you're sure you have the correct account number and sort code it doesn't matter what you put in the name field - it'll end up in the account to which those numbers apply. Of course you might as well put your "best guess" into the name field since it doesn't hurt, and in the event that something does go wrong it's backup evidence of your intentions.