Phoned the O2 iPhone line again yesterday and this time I got a very helpful lady. I told her that I wanted to use my Nokia N95 to send MMS and she knew exactly what to do to make it happen. I was able to send and receive picture messages within 1 hour using the settings below.
MMSC - http://mmsc.mms.o2.co.uk:8002
Proxy - 193.113.200.195:8080
APN - wap.o2.co.uk
Username - o2wap
Password - password
Image size - Medium
UserAgent - Nokia N95
MMSC - http://mmsc.mms.o2.co.uk:8002
Proxy - 193.113.200.195:8080
APN - wap.o2.co.uk
Username - o2wap
Password - password
Image size - Medium
UserAgent - Nokia N95