Is it harder to get onto an Msci course than a BSc course?

I would love to do a Geography Msci at Bristol. I got 4as at AS level (Maths, Physics, Geography and Philosophy) and am taking Maths, Geography and Philosophy at A2.
I really like Bristol and want to get in, but am worried that I am setting myself up for failure if I apply for Msci. How much harder is it to get in?

I would love to do a Geography Msci at Bristol. I got 4as at AS level (Maths, Physics, Geography and Philosophy) and am taking Maths, Geography and Philosophy at A2.
I really like Bristol and want to get in, but am worried that I am setting myself up for failure if I apply for Msci. How much harder is it to get in?

To add to the above - what PQ said is usually true - in my experiences they often encouraged applicants to apply for the MSc versions over the BSc versions, and recommend a switch down at a later date if necessary/desired. You're still an undergraduate number in the department, so it shouldn't make any odds as to how many they can take as you count the same.