I have been with this amazing girl for a month now and we have both completely fallen for each other I no she likes me a lot and hasn't given me a reason to doubt her but I still get jealous when she talks to her friends and work colleagues can you please help or advice??

This might be a trust issue. Has she ever done anything to betray the trust between the two of you?

Also, this relationship is still fresh and you need to give it some time. If she has done nothing to betray your trust then you need to learn to be OK it. If there is no trust in a relationship then it will not be a successful one.

If she's given you no reason to doubt her, then it's an insecurity/self-esteem issue. Focus on building your confidence first.

Do you have any reason why she could not trust you? Something she doesn't know? Found that some people don't trust themselves and project this on to their mate. This might not be the case. Just something to think about. They will soon grow tired of the jealous nature.