Welcome Peter,
A fellow Nikon camera user.
To be honest and somewhat embarrassed by my poor geographical knowledge, I hadn't realised that the northern part of Poland was at such a high latitude. I understand exactly what you mean about the weather and there's also lack of imaging time during the summer months.
If you use a full frame camera then pier 6 might be a good option to start with. It is however fitted with a focal reducer giving a focal length of 384mm. The camera with sensor sites of 3.76 microns, gives a plate scale of about 2.0 arc seconds per pixel. The field of view as you've probably already seen is enormous, so for widefield regions it's a real gem.
Plenty of other scopes as well which also makes this site a good place to capture the objects not suited to your own setup.
The downside however for the next week or more is the restricted number of narrowband objects, so while the moon is up broadband is out. In our higher latitudes, 52°, more narrowband objects are circumpolar, so more choice. Hopefully you'll enjoy some clear skies at home right now if you've had your own camera converted or own a Nikon d810a.
Thanks for introducing yourself Peter,
Cheers,
Ray