[MILDLY SPOILERS] -After you complete you complete the Landsmeet you’ll be asked to rendezvous with Arl Eamon in Redcliffe, and once you enter the castle you won’t be able to travel elsewhere. Personally, I try to complete every sidequests before I complete
the Landsmeet, just to be safe.
The only sidequest that requires you to complete the lasndsmeet is ¨The Tears of Andraste¨.
I found a couple of the side quests do not finish unless you do some of the pre-landsmeet missions which open the alienage and other areas of Denerim to find what you are looking for to finish "missing in Action"/the one for the Fazzel's request, and the
blackstone irregulars Greasing the wheels. Warrior seems ot not get Tears of Andraste or even see slim couldry at all.