Yeah, I would definitely freeze it and use it later on. I have to freeze just about everything in this house or we'd end up wasting sooo much!! I find chicken (and cooked meat in general) tends to be a bit dry when thawed so just keep that in mind, lots of mayo or some other condiment (chutney, BBQ sauce, whatevs) to go with it will fix that right up
Or, you could do my mum's trick of defrosting the frozen chicken, then just chucking it in a suacepan with a bit of chicken broth and warming it up like that. It moistens it up really well and gives it a bit of extra flavour That way you can give your lovely girl a break from sangas and maybe do some rice or steamed vegies etc to take and warm up at work? HTH!!