My face was 100% fine after blue light, but that is because I didn’t have anything to go after. My derm sent me to UCSF dermatology to have it done, and normally they have you come for a few sessions, but the guy said I only needed one because he could tell there was nothing on my face that needed more zapping. If I recall, I would have had some scabbing pimple-like things if I had some things brewing under the surface. Not sure how I didn’t after going to school in FL!? The impression I had was that blue light is not for serious cases. You might want to research that more because I really don’t know.
It was out of pocket for me, too, and it was very expensive, so yes, it was a bummer there was not a little beautifying effect afterwards. The good news is I don’t have skin cancer, so there’s that 
And yes, what your doc said about it only affecting the spots on your face if you have something there is exactly what I’ve heard. To put it in perspective, when I used efudex on my forehead, I only used it on a qtip sized spot, but even in that little area, it looked NOTHING like the photo you shared. It hurt but it was just a little spot of puffy and pink irritation. It never scabbed or turned red. The nice thing is if you do put the cream all over your face and there is a lot there, it will start to hurt etc, and then you can just choose to stop if it becomes too much (which means you would still need to find another way to treat it). So, it’s not like you put the cream on once and then you become that girl in the photo… that is if you keep going.
I talked to friends after my derm said most of her big tough guy patients can’t finish the treatment, and the guys said, it’s not bad a the begining, but when you have to put the chemo cream on your already irritated face, it’s life altering painful
I know a few guys who did tough it out but they said it was brutal. Keep in mind, once again, I’m talking about efudex and not the cream your derm is recommending. I knew one guy during his treatment and he had a LOT of things to go after, and therefore, he had baby skin afterwards… and he also said there is no way you can do this!
I’d say just pick a random spot and use it there… having one painful square inch is very different than having a painful face! So, on your forehead, do it on that spot, but maybe make the area bigger than it needs to be. And if that isn’t too terrible, then you know you can handle it on your entire face later… or just bits at a time (that would be my plan!). And yeah, on the skin that doesn’t have anything, it won’t be so bad.