Hello there , and welcome
Well , it really depends on what car and track you like most and what one you want to learn first before moving on.
I would recommend the training sessions in LFS , then a little bit of Single Player with about 10 AI cars
Just to get into the racing side.
But certainly dont be afraid to make mistakes online too , most drivers are friendly indeed and its v. common indeed for good drivers to make mistakes on laps or even entire races in a server.
Just today , i was on the T7R server ( a well known , high quality racing team ) in a FOX , a car i have never driven before since getting S2 Licensed on saturday , I drove about , came off about 11 times , didnt finish 3 races and only got a 1:07 before calling it quits ( the others were pulling 1:01s every other lap ).
So , you may in fact find others who are also learning ! There really is no specific server i can think of , just use sense , and if there is a BF1 Grand Prix with 63 laps and 24 cars driving in it , then that really isnt the time to take out that UF100 that you have never driven before
Thanks and good luck
Calum