No need to apologise I'm just glad I edited my original post...
I emailed IDNet again last night providing the info I posted here with the test file from download.microsoft.com heres the reply.
"I am confident that your line and equipment (router, PC etc) are working correctly. I also know that our own network is operating with plenty of available capacity. This now leaves either the download site which, as it is Microsoft, I strongly doubt is the cause or that your Exchange is over-subscribed as so therefore experiences congestion during peak hours which are usually early to late evenings. We will try to establish this fact with BT but sometimes they are either unable to provide the data or are reticent (for unknown reasons) to supply such information."
That has to be the most positive reply I've had since they confirmed past problems were due to an issue with a Peterborough BRAS. SO cheers for the suggestion about downloading a file from microsoft...
However last night after I went to bed I left my consoles and 2 of my PC's on, and both the consoles and various network sensitive applications on the PC's all had been signed out at some point between 11pm and 11am. No scheduled maintenence as far as I can tell and I know the 360 if I sign in and leave it on I don't get automatically signed out at least in the past various friends have complained that I've been away at the dashboard for I think my record was 25 days

The PS3 I'm not so sure about as the PSN is a bit poor.
So I'm not sure what this suggests - I did check my router log and the wan as been active for 36 hrs (its quite low as I switched routers when I was experiencing issues on thursday to see if it helped... It didn't)
SO anyway thanks for your help.
I did sign up with the IDnetters forum but I'm just considering how best to pitch my post lol.
Oh ignore the new sig - if it shows up