Try to resist using GPRS abroad.
You will be charged daily for the Access Point and it will end up costing an arm and a leg. Then you will be charged for the data downloaded.
Whilst on the subject of foriegn calls. If you do travel abroad and are on o2 and dont need your 901 answering machine service turn it off! (1760 off 1750 on).
You will be charged for the person to call the country you are in, then charged to have that call routed back to UK. If you listen to it you would then be charged a 3rd time.
If you do not have ITS even in France it would cost you over £1.50 just for the person to leave the meassage per min, not mentioning the call charge for you to listen to it.