I am using a SGS locked to the 3 network in the UK, due to my contract ending I need to unlock my phone from 3's network and I wondering whether 3 will be able to get the code from Samsung or not?

I have tried using the unlock app to no success and also the guide from the XDA site but again no success. I am on Froyo (unrooted)

Any advice would be really helpful.

Unlock codes are based on the IMEI of the device. This is something the carriers do themselves and you shouldn't have a problem getting an unlock from 3, depending on their conditions [time with them, standing of account etc].