Acoustic, self-op studio

I'm a string arranger and I work by tracking up instruments and players. An odd way of working, I know, but it works for me and I'm making a living at it. I have a small recording facility at home that I self-op (a small, dead space), then use bigger studios round Manchester UK when I need to/can afford to. My recording gear (Mac-based) is in the same room. I'd like to improve my primary space and rent a local room that is about 24 square meters, in an old hall. What I'm struggling to learn is what 'temporary' materials I could realistically use to sound proof the space and create a good natural acoustic, suitable to bring the best out of violins and cellos, usually only 1 or 2 players at a time. 'Temporary' simply means a construction I could put in the room that I will have to remove at some time in the future when I no longer rent the space. My current small, dead space is OK; I send stuff out and clients are happy, but I know I could improve my work with a space that gives something back to the instruments. I'm a newbie here and any advice will be gratefully received.

"'temporary' materials I could realistically use to sound proof the space and create a good natural acoustic" Doing a temporary build is a lot more difficult then you might think. Others here will say it cannot be done, but since I disagree with most people anyway, I can only say this: If you do not know how to construct in general then you most likely cannot do a temporary sound proofed, what we call sound isolated, environment. It doesn't help that we cannot see the room in question to add educated guesses on where you are going to need to target your isolation requirments OR what needs to be remove in order that existing materials do not impede your goal of a natural sounding room. If all you are really wanting is treatment that is a lot easier, in my opinion, since there is a basic cookie cutter method that has been used with much success in small rooms. It isn't rocket science, it isn't really science at all, just placement of specific absoption in specific places for specific reasons. Kinda like making a sandwich with bread, mayo and steak, put them together the wrong way, it still tastes great but looks funny and makes a mess. Do you have any pictures of this room sir?