I've had IPL on my underarms as I have really sensitive skin so I can't shave or use hair removal cream under there. The treatment is very good. I have had six sessions now and the hair is almost all gone, and any hairs that are left are so light you can hardly see them. I will have a few more treatments to get it all removed, but at £90 a go I have to save up!
The way it works is you have an inital consultation to make sure the treatment is right for you, and then they take a patch test (mine cost £25) to make sure there are no adverse reactions. If everything is ok then the treatment starts. You lie down and put on a pair of goggles (to protect your eyes from the laser). Then a small gun is placed next to your skin and a pulse is fired onto it. It doesn't really hurt- it feels like an elastic band being pinging onto your skin. So it's uncomfortable but bearable. Both underarms took about 10mins in total to do. Now, nothing will happen for the first few days but within a week or two all the hair will have disappeared. I started to notice regrowth about a month after that.
With regard to not going out in the sun; that wasn't really an issue for me because for one thing it's my underarms which don't get much sun, and I'm not really a sun worshipper anyway.
You say you want it done on your face, well that's fine but you should bear in mind that for the maximum affect of the IPL the difference in light and dark between the skin and the hair should be as much as possible- to allow the lazer to be really concentrated on the hair and not the skin. So by that rationalle IPL is more effective on white skin with dark hair than white skin with blonde hair. (I'm using white skin as an example so aplogies if you aren't white- but you get the idea!) It's not that it won't work on blonde hair, it will just take longer to remove it all.
So if you do bleach your facial hair you may need to stop that if you get the treament. And remember that the hair loss wont be untill a week after the treatment, so the hair will still be there.
Also for the treatment there needs to be a hair in the hair folicle so it can be burnt out- that means no waxing before treaments- leaving your only option to be shaving or hair removal cream which you may not want to do on your facial area. However, speak to the person doing your treatment, they may have an alternative solution.
I don't know if you have a place in mind to go to, but just make sure you check the place out. Since the popularity of IPL lots of these clincs have sprung up, just remember you will be trusting someone to use a laser on your face- make sure you are happy with where you are going. It might be too far away for you to go but I go to cosmetic clinic in north Essex that I could give you the details of if you are interested.
I would really recommend this treatment, I've had no problems with it. Hope that helped.