Research experience to enhance my cv

im a last year biomedicine student in spain. I recently completed a summer reseach internship at oxford, even though it was a research internship, I didn't get to publish anything. I have loved my stay in oxford and I would love to pursue graduate studies here. I talked to my PI about this and he told me that in the future after finishing undergrad, I could pursue a PhD here (having a master's is not a requisite). However he also told me they take into consideration all your previous research experiences and if you have any publications... this kept me thinking, how could I have any publications as an undergrad? who could I ask about this?