Depends where in the uk you are.
It might be an idea to check the status page on VM and see if your area is inundated with problems.
If you're ex-blueyonder go to
http://tools.blueyonder.co.uk and that will tell you your ubr.
Mine for example is: Client Host Name: XX-XX-X-XXX.cable.ubr01.uddi.blueyonder.co.uk
If you're really nosy, like me, once you know your ubr, a call to tech support to query problems on that ubr would also be a good indicator.
Yes its 25ppm, but I'd be nosy enough to find out.
If you do decide to upgrade, remember to state your upgrading for 30days as a trial and that you don't want tied to a new 12month contract.
HTH
Mags