The Electronic Medicines Compendium (
http://www.medicines.org.uk/emc/ ) do a good SPC (Summary of Product Characteristics) on sodium valproate. Don't look at the PILs (Patient Information Leaflets) because they're far too basic.
I have never taken it, but if you want I can do some research from my Psychopharmacology textboooks for you and PM you the details.