One reason it doesn't happen the other way round is language again. We have the burden of English being spoken as a second language in many other countries, so there is little incentive to really push language learning in school here. It's foolish, but there is a logic.
As the UK becomes poorer compared to the rest of Europe there will be those that will wish they could speak a second language. Not that it will do much good, as post-Brexit unless you are rich or a high performer there is very little chance of landing a job. The British population happily voted away that right.
Immigrants settle in all rich countries not just the UK.
Just because there is a queue of 100s at calais to get in, doesn't tell the whole story of millions of economic migrants travelling all over the world.
key part here
Those who try to cross the Channel planned to come to the UK since the beginning of their journey, mostly for cultural reasons.
The few refugees that choose to cross the Channel do it because they have relatives or friends in the U.K. and take significant risks to cross the channel.
Considering the part of the populations that keeps voting for xenophobic Tories, that the whole country threw a hissy fit about immigration in 2016 and has been hardening its stance by the day since, and the pile of scandals à la Windrush, the reality is somewhat more nuanced than that.
> They also speak English, which will also be a driving force from certain countries.
Yes, this is an important motivation. There is also the aura from nearby commonwealth countries. The UK used to be good at building soft power.