You know you might be an enthusiastic person by having more and more time in order to prepare yourself for CSS. Kindly don't take risk by counting on BA degree only because variations can be appeared in the rules at anytime as the bill is already on its way. Go for Master but start preparing yourself for CSS right now, Yes from now. Start Pre-Preparation Onwards, if you know what I mean. Don't miss the chance. Master will flourish and revive all the weak areas of your life and your study in almost every subject. Master mentally always appreciated. One thing I've noted (personal experience) BA/BSc students are appearing so arrogant always. They are NOT so matured. Further it will help you in interview too and will make you more confident about yourself Insha'ALLAH. In a nutshell, I would rather suggest you to Go parallel with both of them from now.
Note*
These my opinions only, do what your heart says. Actually after my BSc I was so weak in every aspect, So for CSS master seems very suitable to me
Regards
Farhan khan (Master in physics)
Sent from my SM-E500H