If it's a new job, learn R.

You've signed up for something, so take responsibility for it. I appreciate your situation, but if you've agreed, man up.

You can think this is belligerent, but I personally have had to change up many times in my career(s). I had to learn Python! (it's not that bad though).

I like that other Monks are trying to help, but my advice is this: You have a new job that you've accepted, so learn the ropes of what they want. During this time, expose and explain your experiences elsewhere, and see what type of feedback you get. If you get none or the response is hasty or of a quality you don't like, quit and move along.

As far as the right "coding environment" or "learning style", you won't get that until you actually bite into the new sphere, and get an understanding of it. I have worked in so many industries doing so many things, that it is impossible to accept new practices until one has some experiences.

I say get a feel for the position, get an understanding if your employer is ok with you testing out new/different methods of production that may not be the norm, if you have them, flex some muscle, and if you can't flex, start looking for new opportunities.

Jobs don't typically last 10-40 years like they used to... get in the game; the employment world is literally a roll of the dice anymore.

ps. it doesn't hurt to learn new things, in this case a new language (if it is a language, I don't know). Take what you can...