May we assume a typo in your post? You've told us that you were working (and claiming benefit) during the tax year 16/17 but you then go on to say that you stopped working before the start of that tax year. ("March 16"). I'm guesing that you actually meant March of
this year.
Anyway, HMRC will expect you to pay in one lump sum IF you're able to do so. Otherwise, as long as they're convinced that you'll pay up in the end, they'll allow you to pay in instalments (but with interest added).
This link doesn't specifically relate to your circumstances but it still serves to illustrate the general policy that I've referred to:
https://www.gov.uk/difficulties-paying-hmrc/youve-missed-the-payment-deadline
(See "When you might get more time to pay")
However you might not even be billed. I receive pension credit and (being an honest citizen - well, most of the time, anyway!) I declared some income I received in the past tax year, using the phone number I was told to call (even though I knew that I'd have to pay every penny back, meaning that I'd have effectively worked for nothing). I didn't get a bill at the end of the tax year but, when I later reported some income for the current tax year, I was told that I should have filled a form in at the end of the last tax year (even though they never sent me the form). I've since completed that form and submitted it but, many months later, I've still not received a demand for repayment. I've now reached the stage where, having met my legal obligation to declare my income, I'm not going to complain about the absence of a demand for a refund of my benefit!