Britain would've been in a far poorer position for the coming events if he'd taken the opportunity to erase them all there and then, there's various theories as to what happened and why the panzers were held back, it's debatable how much input Hitler himself had on the matter. The terrain was not ideal for the tanks to roll into and counter attacks were surprisingly effective in creating hesitation. There persists a theory that Hitler was rather reticent to render the uk such a devastating blow, losing 330,000+ at that stage would be absolutely decisive. I don't think things are as simple as that but it is curious how Hitler actually admired the british empire and didn't want to destroy it the way he wanted the soviets to disintegrate, he wanted to ''co-exist'' alongside it (yeah right for how long?) and viewed the british as worthy and valuable and respected them as comparable lifeforms in his twisted vision of the world. He hoped for 'peace' with the uk for a long time and genuinely could not comprehend why Churchill was vehemently opposed and disgusted by such a concept, there's no way a world power would stand for a dictatorship cropping up and taking over half of mainland europe and mainland europe's far flung territories just for starters at the basic level, the man was deluded as much as he was on the ball, he should've ensured they were put out of the game like France, britain was always going to be a landing strip for america whom he considered a nation of cowboys with no stomach for a fight but admired their ability to mass produce.