The number of boats crossing the English Channel by immigrants has fluctuated significantly in recent years. In 2023, over 45,000 people crossed the Channel in small boats, according to the UK Home Office. This marked a continuing rise from previous years, with numbers increasing since 2018.
In terms of daily or weekly numbers, it can vary depending on the weather and other factors, but it's not uncommon to see dozens of boats attempting the dangerous crossing on a single day, especially during the warmer months. The UK and French governments have been working to curb these crossings, but the problem persists due to the high demand for asylum in the UK and the relative ease of making the crossing compared to other routes into Europe.
Try and do it yourself. I used an agent for my first year in Phuket. It was extremely expensive and it caused major issues when I attempted to renew the next year.
Give yourself plenty of time. It really doesn't matter if you have to visit the immigration office a few times.