It varies from person to person. Because you can include so many other beleifs into Druidry I would say that its practitioners believe a great many things about what happens after death and suicide. I personally believe in reincarnation, so in my opinion suicide would be somewhat redundant.
In my opinion, if reincarnation exists suicide would be pointless and meaningless. This is because ending life wouldn't really be ending life, you would simply move on to another life and have to start all over. We all experience similar problems even though our lives aren't exactly the same, so to me killing myself would just make me experience again the phases of my life that I've already been through. To me the concepts just don't make sense together for the most part.
I agree with Ruby, I also believe in reincarnation. I'm not gonna go deep into it because some view it as a sensitive topic, but if someone commits suicide they would just be starting a new life, depending what is going on that the reason they are committing suicide some view it as "starting a fresh new beginning so they don't have to deal with the struggles" but I do not because everyone is gonna have struggles some point in their life and it will go on and on.I say live your current life to your fullest. You will get many different opinions on this.
I hope you'll forgive the intrusion. I'm offering an opinion as a non Druid. I'm doing so because I'm worried about the questioner's well being. I have struggled greatly with suicidal ideation. I finally promised my God that I would stop and that has helped some. I also receive medical attention. I would like to point out that I think we all dwell in a great circle. Each of us has a place in that circle that is meant for us. If you abandon your place you really really really screw up the circle in ways you can't imagine. It's not fair to everyone else in the circle to do that. That's just my two cents.
If your talking Druidic views as in the ancient celts, I can't speak for sure on their societal views on it, but in the religion they believed you go to the otherworld and then are reborn through reincarnation so there is not really a negative punishment aspect, but I agree with the above comment, don't kill yourself if you are going through hard times try to reach out for help and talk to others, I've been through dark times where I contemplated suicide, but I'm glad I chose not to go through with it.