To the OP,
In my experience, if you are prepared to do this, your employer will be prepared to allow you. In other words, you may be making the situation worse for yourself by agreeing to it.
I am guilty of having done this in the past, but when challenged, most employers will see reason.
First places to look for guidance:
- your contract of employment
- your company travel policy
Mine makes no reference to travelling on my own time, but if I permit other people to control my schedule or travel plans, they will invariably choose 'own time' travelling. In reality, the company does not expect this, but one has to be firm about it. Talk to your manager and explain the impact that doing this has on you
and the company.
As I spend so much time travelling (I am in an airport lounge now), I am much more forthright, so I keep control of my travel plans and unless it suits me to do so, I won't travel on a weekend and if they put me on a red-eye in Y, they lose one to two days of working time depending on the number of timezones crossed.
As long as it doesn't mean becoming unemployed, just say "no".