Homeless - that really is cheeky!!! Its also very annoying that people could hear your less than perfect debut - but don't let it put you off!!!! Everyone knows that people's level of performance changes over time & with circumstances. And the audience for the tape is likely to be similar to the audience that was there - ie they will be interested to listen, will be impressed that you got up and did something, and will take it for what it is (a tape of a singaround, not a professional studio recording).
I bet it doesn't sound as stumbly as you think anyway - its generally only ourselves that hear our stumbles. Remember back to how pleased and relieved you were at the time, and think how much more pleasure there is to come.... get some practice in, then go treat your guitar to another night out.

Kris