Hello @marekkaminski :)
I can see, that you also have initiative towards creating and joining these kind of meetups. I am sure, that you experience in creating events would help in it.
Your ideas are nice. The open spaces are good option, mostly in warm months (we can do it in non rainy season in UK) ;)
I am looking forward to speak with you.
Please write me on steemit.chat on my private message (I am @abc.of.love there).
All the best and have a nice day :0
Peter.