Lord...

[Harvexha]

The lord does not let go on vacation.
Last rank, in service 1 year.

[echo268]

What is your relationship value?

[Maester Rawl]

You need to have a 10 relations with the lord to get leave. Speak with your commander after larger fights to earn relations with him or her. If you enlisted with an honorable lord, you gain relations with them as you gain a positive reputation.