Even if you do reach the UK on one of these dangerous routes, there is a high chance you will be caught and removed upon or after your arrival. If you are eligible to apply for asylum, you will have to do so in the first European country you passed through due to an EU law called the Dublin Regulation. This law means that asylum seekers are the responsibility of the first European country they reach. So the UK may return you to another European country if you want to claim asylum.
If you are not eligible to make an asylum claim, the UK will return you to your home country. If your asylum claim is rejected and you do not voluntarily leave the country, the UK Immigration Enforcement (UK-IE) may arrange a forced return at any time.