Hello Marpu, 

Andhra University usually accepts 10+2 certificate but since a diploma may be considered equivalent to an intermediary course, the university may consider it (you will find out during the form fill up process).  Andhra University accepts applications for admission online and usually admissions take place through AUCET for UG courses. Their admission form was available here: https://apunivfgtvj.azurewebsites.net/index_controller_AUV/view?course=AUCET#no-back-button

I am afraid online registration is over for the year 2019.

Hope this helps.