You'll only need to remove the front fairing piece, the sides can stay in place. A second set of hands will be helpful while you disconnect some wires from the relay pack and headlight. You'll also need to unscrew the beam adjusted that's located in the right fairing pocket.
The headlights are an assembly, and well it might be possible to replace a lens, the assembly's are on ebay fairly often. At a considerable savings from Triumphs pricing.
Just make sure to get a North American spec'd part, as other countries have their dip beam opposite ours.
Another option would be to glue a piece of lexan over the broken lens while you're searching for a replacement. At least you can keep riding

till the parts come together.
Andrew