The standard level gives you a buffet meal and one soft drink at the following:
Plaza Gardens - Disneyland Park
Agrabah Cafe - Disneyland Park
Restaurant des Stars - Walt Disney Studios Park
La Grange - Disney Village
Chuck Wagon Cafe - Cheyenne Hotel
La Cantina - Santa Fe Hotel
Crocketts Tavern - Davy Crockett Ranch.
If you want to eat at a higher category resturant you can put your voucher towards the cost. Your standard vouchers are worth €29 for adults and €17 for children if you use them in that way.
You can book tables online - but not via the UK website, the Dutch one allows this though - open this link in google chrome and it will translate to English for you:
disneylandparis/nl-nl/restaurants/
Hope that helps.