Scouting parties are constantly returning with any news. You command your people to behave themselves: no firing of buildings and no molesting the inhabitants: you will not have it said that William of Normandy is a bloody-handed barbarian toward his future subjects.
Soon, you receive confirmation of the rumors: that king Harold has won a great victory against the Norse near York, and killed their king, Harald Hardrada, and Harold's brother Tosti. He is now marching rapidly southward to engage you in battle.
Many of your men are obviously very frightened at this news. It is a good thing you have stoutly fortified the camp, so that those of weaker mettle can have a secure place to think matters over. You encourage your men: reminding them that it takes heavy casualites to defeat a foe as doughty as Hardrada: "How many of his best troops can Harold have left, after such a victory?" That makes sense, and your troops are willing to wait and see, their fear greatly diminished. Then someone wants to know how you are going to face the Norse fleet in English hands? You assure them: "Doubtlessly, Harold has a great many ships now to add to his own: but how many men, think you, does he have? Each man he puts out to sea is one less fighter that we shall face in the deciding battle soon." That makes sense too. The feeling in your fortified camp is one of guarded optimism You have instilled courage in your men with your fearless example and careful planning.
But Harold stops his march at London for several days, obviously reinforcing his army. So now you:
March west and north, to outflank the English army and threaten London.
Withdraw your troops to Pevensey and fortify yourself in the old Roman fortifications there.
March toward London, and send emissaries to challenge Harold to battle.
Stay based on your fortified camp, and send out raiders to pillage Harold's lands. This may bring him down to battle faster.