French Alps holiday help!?!

Leah
Hi all
We have a holiday booked to Val thorens in March (I will be 29/30 weeks while we are there) 
We're driving over so flying isn't an issue, and my doctor and midwife are happy for us to go.
Just wondering what all your thoughts and advice are?! My family will be skiing (obviously I won't) but can spend the week relaxing and wandering the shops/spa!
Do you think I will be ok with the altitude?! Any advice from anyone whos been while pregnant? 
Xx