Yes you’re right, but there is far more legal migration than those arriving illegally.
There is a large black market in non existent jobs, social media is awash with dodgy job offers, many entering the country via these routes subsequently seek asylum. Many others are students who do not take up their courses and then disappear into the black economy. HMG are bringing in legislation to address these routes, though a massive reduction of overseas student visas being issued is severely affecting colleges and universities.
The language tests are pretty easy, it’s the Life in the UK tests that many struggle with.
Of course the boat people are an issue because they’re in the public eye, ideally they would build more Immigration Detention Centres, but there is a massive NIMBY movement making this difficult, hence the use of expensive hotel accommodation.