Yes, they go into the 2nd qualifying round and then a 3rd qualifying round before the groups. They're currently 2nd seeds in the 2nd qualy round behind BATE Borisov and assuming all goes to form would be 2nd seeds in the 3rd round too. So they should go through if there are no surprises.
EDIT : There's a FOURTH qualy round! They'd be 2nd seeds in that too but it's not exactly full of muppets. Likely to be sides like Dinamo Zagreb, Partizan Belgrade, Austria Vienna, Legia Warsaw. Sides capable of upsetting Celtic.
where does the 4th placed English side enter? I could look this up myself of course, but it seems like you've done your homework.