sous vide vs slow cooking
This is more for slow cooker / crock pot.

If it is single or double meal size and you cut up the meat and other ingredients then you should be fine.   

Meal for 4 frozen hard, large pieces, and you are not there to stir it is going to have the bottom more done.  You are probably not going to create a food safety issue of any part between 40 F and 140 F for longer than 2 hours.

Pull it before and let it defrost all the way or at least partially in the refrigerator is a much better plan.  You would want it defrosted enough that you can spread it out in the pot.

If you are only going to cook a single then get a small slow cooker. Consider two meals and then just refrigerate one - it will be good for 3 days and slow cooker meals tend to reheat nicely.

Can also go the other direction and cook four fresh.  Eat one, refrigerate one, and freeze two.  Most of the crock meals reheat nicely.

Slow cooker versus sous vide is a bigger question and likely a duplicate.