Now that you know the location of the bandit camp, it is time to scout it out in preparation for an assault.
Note: In order to successfully sabotage the encampment you will need to have a few vials of poison in your inventory. You can either brew these yourself or buy some at an apothecary.
You can begin your journey to the bandit camp by riding to the woodcutter's camp mentioned by Timmy, located north of Talmberg.
When you reach the entrance to the camp, it is time to scout the area and sabotage supplies. There are two main ways in which you can do this; poison food and set fire to arrow reserves. Assuming you killed Morcock and his accomplices, you will have to keep out of sight as much as possible.
Note: If you chose to aid Morcock in finding Timmy, you will be relatively free to roam the camp for a while, but do not linger for too long in particular places, regardless of what the bandits say.
Once you have cleared the area of patrols, walk around the northeastern side of the encampment until Henry acknowledges some useful information.
With the camp sufficiently scouted, you can now poison food supplies and burn arrow reserves. Note that the quest objectives may not update once you have carried out the sabotage, but it will be recognised by Sir Radzig when you return to him.
The key here is to be patient; it is likely that most entrances to the camp will be patrolled at any given time. From the stockade entrance, wait and observe the patrols. Choose the right time to attack when there are minimal bandits and Cumans in the area. You may need to take out one or two static guards by stealth kill or by shooting from afar.
Note: If patience is not your forte, you can equip some Cuman armour to disguise yourself and wander into the camp unquestioned by bandits. You can get the armour from one of the patrols, or from the chest in the stockade. There may be some inquisitive Cumans who question you, so be ready to answer with your best persuasion option.
With all objectives complete, report back to Sir Radzig in the camp north west of Merhojed. Depending on what you managed to accomplish at Pribyslavitz, you should inform Sir Radzig of your discoveries. It is best to notify him that there are a lot of foes and that the archers are well positioned.
Ride to Talmberg to request aid in the form of reinforcements from Sir Divish.