Thanks for your help! I've set everything up the way you suggested and *touch wood*, all is going well.

Seems I picked a bad day to test my speeds; I thought at the time my upload speed especially was on the slow side.... thankfully it seems to have gone up much higher now and has stayed there; which in turn has made configuration much easier.
Uploads are still not particularly fast, but at least they don't keep going backwards and stopping at 0/KB like they used to.
Though I think perhaps that could be something to do with how many upload slots I've allowed per person and the maximum slots - I'm still not entirely sure quite how many I should be setting it all to....
My downloads though are much quicker.