Suggestions for connnnnnnnnnnnnnnnnnnving shed to music room

I am a new songwriter and am looking to convert my 3m x 2m shed into a place I can go and write music without annoying the neighbors too much. I have a limited budget so I want to keep it as inexpensive as possible. It does not have to be recording studio-level just enough to not annoy the neighbors. I am considering Producers Choice Blankets from the USA. I am located in Adelaide where the temperature in Summer can reach 40+ degrees Celcius. I would appreciate advice only for now, please!

My apologies for the repeated letters in the post. My computer is playing funny buggers on me.

Thin metal shed, also presumably far from air tight? To do this cheaply is unrealistic - you'll basically need to build a whole new structure within the metal shell. I think it would actually be easier to build from scratch. Blankets aren't going to do much of anything, other than make your shed's interior sound less reflective.