Hi Bugs
I did just that just over 12 months ago. First I got the venue, by going round all the pubs to check them out and asking at the ones I liked the look of - and one which was in new ownership, said yes to a regular monthly session.   Then I took the plunge and advertised (with beating heart and thinking no one would come!!)   well it just took off, attracting players of all abilities and all instruments so that at times we have struggled to seat them all!!) theres a wonderful atmosphere, we pass around tunes we like and ask people to learn we give advise and support to new players - its proved to be a very good experience.
So, go for it, suck it and see, and good luck
Lin