Hi Chris, and welcome to the forum.
You have already received some good advice, but I would like to offer you a few observations of my own.
I began by purchasing a second hand 12 Bass Galotta, which suited my needs at the time. I then went on to buy a second hand 72 Bass Chanson, as I felt that I needed a few more keys to play with.
One old bloke I know plays a grotty little 8 Bass instrument, of unknown origin, which he plays very well indeed. A friend of mine from the Folk Club also plays a little 8 Bass, which he carries around in an old knapsack. When he drags this thing out of the knapsack, it looks like a battered old biscuit tin. Still, he knocks out many a good (if simple) tune on this old tub.
I suppose what I am saying is that you needn't necessarily go out and buy a shiny new instrument, and that what and where you want to play should guide your decisions. I only play in Folk Clubs, though I don't only play folk music. Hearing and playing along with other instruments and very good friends is my ideal, and we have a great deal of fun doing it.
Please consider joining a local Folk Club. I'm sure you will find that the other members will be supportive and generous with their applause, and will appreciate any effort you make to contribute to the evening's entertainment. You may not feel confident enough to play on your first visit (I wasn't) but any trepidation will very soon evaporate as you become part of the group.
I hope some of what I have written helps.