See figure 1.3a - https://www.gov.uk/government/publications/migration-advisor...
Note that to the best of my knowledge, these numbers don't include the Afghan resettlement scheme which would further lower the proportion of employment driven visas.
Study visas do not have a pathway to settlement. Students paying through the nose for the privilege of staying for a few years to study and then leaving (or getting work visas like everyone else) is hardly a bad thing.
"The use of the UN definition of long-term immigration means that whether someone should be counted as an immigrant or emigrant (and hence contribute to the net migration statistics) only becomes evident after 12 months.... Currently, the ONS publishes provisional estimates with a 5-month lag"
The discussion of international students is less relevant to employment related concerns, but still contributes to other aspects of population growth like rental housing demand or water consumption.