Dear Avi, I have done DT and IDT at my own. But yes, I took classes of ICAI. And it was my good luck that at that time Girish Ahuja Sir was faculty of DT for ICAI. So it gave me a better confidence in DT. Although his classes were very few. I read from his book only. For IDT also, I read from Ajay Jain Notes. I was taught basics of IDT by one of my friend, who was taking classes from Ajay Jain, and then I prepared it by self study. I scored 55 plus marks in DT and exemption marks in IDT. I think these were satisfactory for me. So, I dont think its compulsory to go for coaching, if you have a good environment for study and having a good friend circle with whom you can share your doubts. If you are from Delhi, then I will suggest you to join ICAI classes alongwith the self study, and make a good friend circle of 3-4 friends in CA final.
You have sufficient time for study. If you are from Delhi then I will suggest you to go for Liabrary of ICAI for self study. It have a very good environment for study. Discussion with friends is the most important step for self study. I took classes for MAFA only in final, and rest study was done by my own.
There are certain other techiniques of preparing Taxation papers and presentation in exams. I have written an article on it. If you want it then send me a test mail at tarun2507 @ gmail.com. I will send that article to you. It had helped lots of students in last attempt. Hope it will help to you also.
All the best.