You might be better off going through the quest, my first run I ended up staying in Rattay for weeks in game (after that horse stuff so Bernard was back to train with). Ended up getting OP and enemies scaled up and I missed out on big chunks of early/mid game enemies and combat. Restarted on hardcore, with numbskull perk to slow down leveling, and basically been going straight through main quests (because yes it does seem constantly moving forward and urgent), and it's been really great.

Recently finished what might be considered Act 1 (or 2) with a major battle and boss encounter, things seemed slowed down and I took time off for side quests for a week or two. I was probably underleveled for the big showdown but took some potions for offense and defense, and having practiced for many hours in previous incomplete run my own skill was higher. Rewarding battle.

If you really want nothing to do with the main quest... I guess just don't. Your Henry could be one who dgaf about the goings on and push and pull of the nobles around him. You might prefer picking pockets for local vagabonds and just traveling the lands following your whims. Should be fine.