Instead of going out all lonely to see the stars, let's share stargazing time and views for safer and more social, better experiences (and learn more)!
We do this locally in South West London (with occasional events elsewhere) and as often as the organiser's schedule/weather permits. Events may be at short notice (~2 days) sometimes if the skies suddenly clear. Hence our calendar can be somewhat random, but we try for at least one event per month, including: star-parties (in a public common/park), socials (pub/cafe), and occasional trips to exhibitions / observatories / other places of interest to astronomers.
We continue to meet in summer. For stargazing, we mostly start by meeting in lit public venues (such as pubs) near a darker location to gather and introduce ourselves; before walking to the darker location for viewing together. I aim to make events reasonably accessible via public transport too. This reduces worries for new members. Its much better than expecting new members to find a small group of unknown people at night in hard to find dark places. Feel free to suggest new events/locations too! (always on the hunt for alternatives in new areas, might you have somewhere to share with us?)
We enjoy sharing views through different telescopes/binoculars, or even with just your eyes; and knowledge about the planets/constellations/galaxies/deep sky objects and how to find them. Several members have telescopes and bring them to some meets, but you don't need anything to come along, just show up. Late evenings are much easier in Winter of course with earlier nights.
Its easy to find talks to go to around/near London to learn and the web always has plenty of news and info, so this meetup group is primarily for meeting up in the evenings to see the stars, the moon, planets or deep sky objects (if there are suitable telescopes around).
Note: due to the weather, meetings may come up at relatively short notice or be cancelled if its terrible, but I plan on both weekdays and weekends, and try to set up at least one or two meets per month. I also copy over and post the Baker Street Irregular Astronomers group monthly (but irregular) events in Regents Park to publicise those as they are great events and usually very well attended (can be more than 100). Everyone from novices/beginners to experienced astronomers go, there can be 20-odd telescopes/binoculars on a good (clear) night brought by members, so they are a great way to learn more and see different equipment and accessories at work.
Some meets will fallback to a social evening inside if skies fail us. If a meeting is described (in title or main description) as tentative or unsure, then please check with the organiser whether it is still on, close to the day of the meet (by phone/text/email, allowing at least a couple of hours ideally in case of delayed response). Otherwise you take a slight risk going.
Use the message board to make random invites if you're planning a session a night or two ahead. It feels much safer and more fun sharing the wonders of the night sky with others.
Common meeting grounds might be Tooting Common, Streatham Common, sometimes Wimbledon Common but we try others too sometimes. Commons/parks mean less streets and lights nearby, are publicly accessible (not always at night), and are generally the best places in London for stargazing. I'll try to keep public transport in mind as obviously dark skies tend to be further from public transport. You'd be surprised what you can see on a good night when away from immediate streetlights though, especially through any enhancing equipment (regular binoculars will do, telescope even better).
For more about our regular locations, see the locations page I wrote about that (in the "Pages" section on meetup website, not in the app).
As I say, you don't need anything but your eyes to enjoy the night skies; there will almost always be at least some binoculars and a telescope brought along by others that will be happy to share views with you (the organiser has some good binoculars, often on a tripod, and a small telescope). But if you do have something you can bring - from as little as a red light torch (which doesn't ruin your natural night-vision so easily), to binoculars (any pair will do!), a camera (better if you can control the exposure manually eg. DSLR/bridge camera), or telescope, then we'd appreciate that and hope you can share views it gives. Even the star-map apps on phones are useful (eg. Google sky map) for finding targets to view. If you can provide transport for others to better viewing locations then thats also very much appreciated.
If you're interested in buying some equipment, do check out my buying advice in the page I wrote about that - but I very highly and strongly recommend you come to an event first (whether ours or another) and see other people's gear and ask questions first because it can easily be an expensive mistake if you don't know what you want, and even put you off for good. Or at least talk to someone in a proper astronomy shop (eg. Widescreen Centre in London, Astronomia in Godalming to name two London/nearby shops), and read a few reviews so you have a better idea what to expect. Time to setup each night, weight/size to carry and put away, accessories you'll need/want (and cost of), what you'll be looking at (planets/the moon? the sun? deep sky objects? everything? daytime use too?), ease of use (type of scope+finder, type/quality of mount, whether computerised/motorised) and how well you know the sky all play a part - not just the cost and scope power!