I'm a little confused, you've been advised to just order a phone line yet the answer you come back with is that when you do they say they all they can offer you is the slowest possible speed.
This would indicate you are still asking for broadband at the same time.
In your case you cannot get FTTC until you have an active phone line. In the first instance order a phone line and nothing else. On the following Friday the database should be updated and FTTC avaiable to you.