That's a tough ruling because it is a cool idea, but also requires careful consideration of the Shillelagh spellcasting requirements and the improvised weapon clauses...
I am going to say no. You cannot treat a torch as a club, but you can light a club on fire.
Shillelagh requires a club or quarterstaff as a spell component. A club costs 1sp, and a torch costs 1cp, which means they are not the same.
You can use a torch as an improvised weapon, inflicting 1d4 bludgeoning damage + 1 fire damage. It has a 50% chance of shattering with every attack.
You also have the option of wrapping the club in oil-soaked cloth, lighting it on fire as if it were a torch, and casting shillelagh on it. The fire will damage and possibly destroy the club, but it is a proper club (that has been treated with oil and dried so that it is serviceable against steel) worth 1sp and qualifies as a spell component.