Can Anxiety Delay Periods?

My girlfriend and I have had protected sex around the time of her lat period, we used a condom, but her peiod is now 2-3 days late. Shes worried and I was worried her anxiety is possibly delaying her period if that is at all possible? What is the chance if any that she may pregnant? We were considering her taking a pregnancy test at a local centre tomorrow, can you do this at a GP's rather than buying them in stores? Thankyou.