If you have good A-level marks, a predicted first or 2:1 in a relevant degree and a decent UKCAT score, then you definitely have more chances. Especially in the interview. If you've been studying biochemistry for example for 3 years you will definitely convince people more in the interview because you'll know much more about how some diseases work and you'll be able to show your passion through knowledge. However, If you don't have A levels and you only have a degree, even if you get 100% in your degree many universities will instantly reject your application. Same goes with UKCAT score.