Hi David, and
If I recall correctly, it's been less than 10 days since you migrated, hasn't it? You may be likely to experience slowish speeds or instability during this initial training period.
Ideally, you need to do a speed test at
http://test.speedtester.bt.com:50301/, but you may need a bit of patience to get it to work, as it's notoriously fickle, and don't worry too much about whatever error messages you get, as most of them mean "I'm busy, but I don't want to admit it".
Alternatively, you could try
http://speedtest.net/, but none of these online testers are all that reliable.
I'll get Rik to pop over here when he's next about, as he's probably the best one to help with IDNet related questions.