My advice to you will be that one must learn as many languages as possible because I always believe that language or tool should never be a barrier for a good Analyst/ Data Scientist.
I think you have made an excellent choice and should pursue it. For R, Here's the learning path that you can rigorously follow to master it:
Also, you can additionally go through this excellent tutorial series to get the basics right.
For Tableau, you can use:
I wish you best of luck for your learning. Feel free to shoot any doubts.