I have run (well light jog) 5k on a few occasions, my first time was 41min, my best is 35 and I seem to average somewhere between the two.
Am I going to embaress myself at a parkrun?
Also with the new year I am thinking about starting a 10k training plan, is this wise or should I try to work on speed and stamina?
If you look at your local parkrun website, you can find out how slow the slowest runners have been for the last few runs. That made me decide it'll be a while before I join in one, as I'm very very slow (fine by me) and I'd be a good 10 or 20 minutes behind the second to last person (but I might volunteer a time or two, to get a feel for how the thing works). On the other hand, someone has to be last, and I'm sure you'd get loads of encouragement - and at my nearest one, you probably wouldn't be last anyway.