Hi DorsetPirate,
I have been several times to the Gorzow GP, and find that flights to Berlin Brandenburg are good to use. From there, it's easy to rent a car and drive the 2 hours or so over to Gorzow. Alternative airports to fly into that are also easy to get to Gorzow from are Poznan (2 hours) and Szczecin (1hour 25mins).
Tickets have been available for weeks directly from the Gorzow website here: https://bilety.stalgorzow.pl/
You'll need to register and then go ahead and pay for them and print them off. I bought several a few weeks ago at 229PLN (about £45).
Hotels in Gorzow are VERY difficult to get now, most will be booked up already and any that are still there will be expensive. My preferred option is to search for somewhere close by and get a room for the weekend at a vastly reduced rate. This year, I have booked rooms at a small inn about 25 minutes away that has a bar and looks simple but perfectly comfortable for around £15 per person per night!
If you'd like any more specifics, please send me a PM and I'll talk to you directly about it.