Yes, Le Semnoz is very beginner-friendly and budget-friendly, it has everything you need and the view from the top (Cret de Châtillon) is incredible on a good day (you can see the whole northern half of the French Alps, basically), BUT:
- snow cover in December is really hit-or-miss, and there is no snowmaking!
- English-language instruction might not be available
- it is not a resort, there is no overnight accommodation (except one hotel): you do not get the ski resort feel.
All in all, I would suggest you have a look at Le Grand Bornand instead. Still close to Annecy, a bit more expensive, but at least you get a proper Alpine village which you can enjoy even as a day trip from Annecy (the bus is easy). It is not a mega resort and there is plenty of beginner terrain. It is foreigner-friendly (popular with the British thanks to the proximity to Geneva airport). It happens to be where I learned to ski (my grandparents lived in Thônes, in the valley), but I have not been back in over a decade.
There is also La Clusaz, but it is busier and the beginner terrain is less good IMO.
School holidays start on the Saturday before Christmas. Weekend crowds are significant if conditions are good, but not unmanageable. You would need to book lessons in advance during the holidays.
So, in a nutshell:
- if snow is good and you want to keep costs as low as possible, go to Le Semnoz
- if not, consider Le Grand Bornand.
