email settings for blackberry 8100 in uk

I have a blackberry 8100 pearl, bought in italy, where i have registered it to TIM network and set up my email account. The provider was TIM and it was working.

But now that I am in UK, I cannot send/receive emails using my UK provider O2. I have a SIM card O2, but if I use it the email doesn't work.
If I try to set up my account using my pc - O2 website - when I insert my pin and imei, a message says that i am already registered with a different provider. In my phone all icons regarding mail are disappeared. :eek:

I need to use this phone in UK, I don't care to cancel my italian settings.
What should I do?
Many thanks!!