Hello Manuel
sounds like you have a great opportunity now.
First off, seems like you are really passionate about your music. The word "Passion" originally meant "to suffer." It is the things we are passionate about that we are willing to suffer for. And this will help you in the long term when things get tough (setbacks are a way of life, but only setbacks! As far as practicing guitar while others are sleeping, could you use an electric guitar with earphones?)
Second, none of this has to be either/or decision. There are many ways where you could stretch this new money longer. How about doing some part time work otherwise?
Third, as far as your job vs. your passion. Reading your post, I somehow get the impression that you can get buy with just a few basic things. Am I right? A lot of people today need a lot of stuff, and thereby are kind of trapped by their work. Then the work becomes a golden cage. In my book, I urge people to put a price on their lives, and establish a comfort point at which they are OK with what they are making but still have room to do what they are passionate about. For some reason, reading your post, I think you could go a long ways on 40K Euros (about what, 55K USD).
You should define what really you want/need as far as the living conditions while you embark on this adventure, weighed against your dream.
Fourth, have a life design moving forward. Where really do you want your music career to end up with? I don't know what kind of music you play, but at 38, chances are you probably will not be a rock star anymore. So be realistic. You probably still can make a good living from it in other ways.
And last: remember that some 50 years from now, you probably will be dust. Sorry, had to throw in a shocker here. But this is your life here, and you only have one shot at this.
Personally, I'd rather say "I tried and failed" than not have tried at all.
I wish you the best life. Enjoy and Be True!
Hanns-Oskar Porr
The Steps of Essence: How to Live Live Well and Authentically
www.StepsOfEssence.com (also on Amazon.com)