I want to travel from Chambery to Lake Como by train and am finding it hard to search for options can you help.
The probable reason for your problem is that you have to use two separate train systems. You take a French TGV from Chambery to Milan Porta Garibaldi, then a local Italian train to Como San Giovanni.
For the best prices on the French train, book direct with the train operator as far ahead as possible. Tickets go on sale 3 months before travel, and the cheapest tickets often sell out quickly. The discounted prices keep going up as the travel date gets closer.
You can get French train times and costs, and make bookings, in English at en.voyages-sncf.com/en but use Antarctic as the "Ticket collection country" in the first screen to avoid being transferred to RailEurope, which usually has higher prices and does not list all the trains. For notes on online booking, see www.nickbooth.id.au/Tips/FrenchTrain.htm
There is no point in trying to buy the Milan-Como ticket in advance over the Internet. It is a suburban service that has no seat reservations (so tickets cannot sell out) and no discounts. Buy in Milan.