Do you have the Free tier where you live? If so, give it a shot and check it for yourself.
The way to deal with the latency is very personal. Each one of GFN users have a completely personal experience/preference on it.
#Concern about latency
hearty pawn
hearty pawn
About the Free tier test, DM me. I'll give you something that will help you to test and decide.
About the latency, check if you're connected to the same server. You can do it by pressing CTRL+N and see the NP name.
Personally, once you subscribe to Ultimate, select the nearest server manually. Don't rely on the "Auto".
Now, back to my recommendation...
During your testing sessions, keep the GFN session stats windows opened. Press CTRL+N (you can press more than once, to hide or show more details) and you should see your current stats.
hearty pawn
This part might be caused by several factors. ISP routing, is the most common.
As you're connection to the same NP, same country, same server... Your ISP might be using different routes to that server.
If it's not causing you issues (like high latency spikes and packet loss), I believe you should be fine.
Take this time to test, in different moments of the day, different games, etc.
If they are open enough to test it for you, sure. I'm the person that always recommend to contact the ISPs and ask them to run some tests. 😅