Thanks for getting in touch, and not to worry about the question. I do actually know Plan My Gap Year as I volunteered with them in Hanoi Vietnam - they were a great company to use. They have a Facebook page too if you want to get in touch with owner Philip for a chit chat before you make any decisions. I actually met him for a coffee before I booked the trip and he answered ALL of my bugging questions.
I hope you do decide to volunteer while you’re travelling, it was such a highlight for me!