hi wassie...!!
in my humble openion, before appearing in css, you should check...

1. To what extent you have covered the syllabus
2. your written expressions in english

if you have covered the syllabus,have good knowledge of current affairs and can express yourself in good english then you should go ahead with your plans... no matter what your qualification is... if you are not satisfied with your preparation, then beside doing your M.A. you should continue preparation for css... People often suggest that one should appear in css after MA, because after MA, you get more knowledge and maturity...
Please remember that success has no short cut...
so dear instead of thinking about B.A or M.A, concenrate on your studies...

Regards...

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- Some men give up their designs when they have almost reached the goal; while others, on the contrary, obtain a victory by exerting, at the last moment, more vigorous efforts than before!!
Polybius