I don't think you know how Border Control works.
If you arrive in the UK without the necessary documents you were taken to a holding centre, those centres have been overrun by the numbers arriving, so they are being sent to other holding places like hotels, disused army camps or even accommodation barges.
Article 31 of the UN convention on refugees states
"Although it’s certainly true that crossing the Channel without authorisation isn’t a legal way to enter the UK,
Article 31 of the UN Refugee Convention states that refugees cannot be penalised for entering the country illegally to claim asylum if they are “coming directly from a territory where their life or freedom was threatened” provided they “present themselves without delay to the authorities and show good cause for their illegal entry or presence”.
A lot depends here on how to interpret which country people are “coming directly from”. It could be argued, for instance, that as the people crossing the channel are coming directly from France—which is not the country they initially fled—they don’t have the right to claim asylum in the UK.