I personally wouldn't go with such a young child, and some kindergartens won't take them as young as that. If there's snow at village level, you will have a hard time pushing a buggy around in the snow also. Altitude could also affect the child if you decide to take them on to the mountain. The 5 year old wouldn't be a problem, but ultimately you'd need to weigh it all up.

Hi!
There is a resort in Finnish Lapland called Levi, it's geared towards families and there is a creche for young children, they even take very young babies. Also it's not very high so altitude would not be a problem and it's great for beginners.
Lapland does not have to be expensive if you shop around and you will have a holiday you will never forget!