Writing a master thesis in a totally new field? One year ago I started an interdisciplinary master programme. It is now time to choose my master thesis topic and the one I have in mind is totally unrelated to my bachelor and quite distant from my current expertise. 

I know, that if I were to choose this topic and write a good thesis I would have to acquire substantially new knowledge &amp; skills.

Although I have 9 months to write my thesis, I am considering taking a year off to get caught up on the said topics, and then starting next year.

Is this advisable? 

Would you take up the challenge to get acquainted while writing the thesis or only start researching after you've familiarised yourself with the basics?
It might be different from country to country, but where I did my Masters project (Denmark) your judged on what is expected to be learned (with of course a basic-level start knowledge) within the allocated time for the project. Hence, I would not advise to take a year out to get acquainted. 

However, it should also be noted that in Denmark you get money to study and so a year of would mean you would need another income. Opposite to other places (like US) where it cost you money to study.