Ah! sorry. I think the answers are approximate and sadly I cannot think of one at the moment. The key point is you will only find out exactly when the BB is installed if it is an up to 8meg or whatever service.
During the first 10 days or thereabouts the line is "maximised" for speed and it will eventually settle down to your line rate.
Incidentally tyhe rate can vary from a number of factors and even a neighbours speed will not be an acurate guide.
I think in all likelihood I'll get somewhere around the 2/3 mb area.
The main reason for me trying to find out what the line can take is so that I don't go for a 'up to 16mb connection' when all the line can take is 3mb (in which case I'll go for something like 'up to 8mb connection)