I will begin by saying that I am not saying you are wrong to be concerned about terrorism. I think with the world the way it is today, terrorism is real and relevant. And it is frightening.
However - you do need to take a deep breath and think about it. you cannot allow fear to make you bigoted or foolish or to prevent you from analysing things or understanding the complexities of the situation. I understand the desire to be safe and the need to look for that Something that can be done that will protect you. But that's not possible, in reality.
Take the link you posted, which prompted you to say we should 'do something' about Calais
The link very clearly reports how people in the uk are making online connections.
'doing something' re calais would make no difference to those people who are in the uk, perhaps born here, and being contacted from their homes in the uk.
It would make no difference to holders of british passports who are not trying to make their way here from france.
The majority of people attempting to get into the uk via calais are economic migrants, not would be terrorist attackers.
When you think about it, the calais route would be spectacularly inefficient for people with that agenda. There is no guarantee of access, no timescale, nothing.
Also, deport them. This is problematic. Who is 'them' ? Deport 'them' where?
You assume that the 'them' are not british. You cannot make that assumption.
Let's suppose I suddenly decide that I'm going to join a terrorist group from the comfort of my living room.
I am british. I was born here. Both my parents were born here. All four of my grandparents were born here. I have a great grandparent from Ireland and one from Scotland. I suppose I could be frogmarched out of England and taken to Kinrath or Dingwall. Or where would you suggest I be deported to?
It's dangerous to think that only a certain type of person is a threat and that you can deal with that type of person. Apart from anything else, it blinkers you and it's important to be balanced and to see that not everyone will be a risk, but anyone could be a risk.
We need to look at what's happening, why it's happening, what's going wrong that people in the uk right now are willing to consider what these people are suggesting.