What I should I be informing HMRC?

Thanks4Help

My partner has just got approval for sabbatical for an year from a public sector organisation. She wants to move to her home country in Asia and does not want to return after an year. But, just in case if there are unforeseen issues that forces her come back , she may return to UK.
This being the situation, how and what should we inform the HMRC, local council, and UK banks etc.?
Can we say she is not coming back for now and then eventually if she comes back inform them? We understand we may have to pay back some tax exemption or anything we get may have to be paid back? Will there be penalty for this?
Please help. Thank you.

00ec25

there are key websites that list the facts you need to read,
.Gov being the obvious start point

http://lmgtfy.com/?q=tax+on+leaving+the+uk