Foreigner travel to Tibet with Chinese friends

You may not need to join in a tour party but you need to have the Tibet travel permit. Without that permit, you can not get the train ticket. Although your Chinese friends can buy train ticket for you, there are officers check your passport, permit in the train. I would suggest you can let your friends search for a Lhasa travel agency and entrust it to handle your travel permit. Then you can travel together with your friends. National Day holiday will not be an issue, just more visitors.