Sorry for the loooong reply, i dont read my vistor messages, you needed the setting for the MMS, as i dont use picture messages i didnt research that, but it does work, as my friend sends messages from his g1 on our tariff.

Hello,
Fellowing your reccomendation, I now have an o2 sim.
However I'm still experiencing problems with the APN settings
I have tried several variations, none seem to work properly.
Currently on my phone I have the following basic settings only:

APN: payandgo.o2.co.uk
Username: vertigo
Password: password
MCC: 234
MNC: 10

Are these the only settings you have?
I get the 3G symbol but every time I try to send a message I get the following error:

Sorry!
the application Messaging (process com.android.mms) has stopped unexpectedly.
Please try again.
Force close

Any help greatly apreciated as its driving me round the twist!

Oh and one more thing, I have registered for the web & wif bolt-on, they said it takes 48 hours to come on, but were a bit suspicious because I haven't got my iphone yet!(heh heh)
Did yours take a while to come through?