As someone who studied law with criminology at undergrad, it is certainly possible to become a lawyer in the future, and indeed I thought that criminology was very useful as a backdrop to some of the things that I learned in law.
As you've not even started your second year, your focus right now should be on getting the best grades possible in your criminology modules. You want to give yourself a good platform for the future, whether that be a legal career or otherwise. It would also be useful to do a bit of work experience in a law firm to get a taster for the legal world. Your focus should then become on whether you want to commit to pursuing law and doing the GDL, or doing a preparation course for the SQE. Once you've done your research and are convinced that law is right for you, go for it! Many law firms recruit individuals who did not do law as their first degree and this certainly is not a barrier to enter the profession.