Yes you can surely do bpp and BA both in IGNOU.IGNOU with an aim of offering education to every one came up with this BPP. BACHELOR' PREPARATORY PROGRAMME which js nothing but a kind of an entrance test which enables a student to enroll for their Bachelor's programme. Students coming from different sections of the society who were unable to complete the education can enroll for this programme and once completing this course, can further pursue their education and complete their Bachelor's degree.
Just pass the BPP and go for your bachelor's degree.But please kindly note that if you are doing BPP from IGNOU,then it is compulsory that you do your BA course also from IGNOU.The BPP certificate from IGNOU will not be valid for doing your bachelors in any other university than IGNOU.
I hope this solves your problem.Good luck for your future.Feel free to ask if you have any further queries.