I am so happy to hear that some of the answers have helped you plan a trip to Himachal. Regarding a budget family trip to Europe, well there are many points to consider. Depending on when you travel and where you travel, ticket prices may be an issue. Try and book ahead for cheaper airfare.
Disneyland Paris is one of the most famous amusement parks in Europe. If you decide on going there, I would suggest flying to Paris from India (Air France has a direct flight from Delhi). Paris is an expensive city but there are plenty reasonable Airbnbs and hotels in the different arrondissements. You would need to commute by train or walk in the city. Disneyland Paris is just 32 kilometres away by a regional RER from the city centre. You need to get off at Marne-la-Valee station which is in zone 5.
As you want to see the countryside, I’d suggest taking day trips from your base. Near Paris, you could visit Versailles, Rouen, Chartres, Troyes, Laon and so many more. Check which train stations you would need to go to and then purchase local tickets instead of Eurail ones.
This way, you will be able to enjoy the best of Paris and have the holiday you and your children want.