Having got my P910i, and getting o2 to send the GPRS settings to my phone, I noticed a small problem.
Whilst the WAP browser worked, Email, Traffic-i, jMSN and Opera didn’t. They all worked before on my P800, and Traffic-i is a subscription service which I’ve paid for.
So as I was about to complain to them, I noticed something on their website: Mobile Web, this seemed to be different from o2 Active. Unfortuantaly unlike o2 Active, they won’t send you the settings via sms. Instead you have to open up PDF documents, which don’t relate to your phone, just to find the settings.
For those on o2 (any new phone), I would recommend adding this Internet Profile:

Name: o2 Mobile Web
Connection Type: GPRS
Username: o2web
Password: password
Address (APN): mobile.o2.co.uk

For a P910i, you will also need to set up a Wap Account with these details:

Account Name: O2 MOBILE
Internet Account: o2 Mobile Web