It’s perfectly possible to apply for any UK visa on your own; in fact, the system is set up for individuals to apply directly. Each UK visa is governed by publicly available immigration law and supporting information for applicants. However, unless you’re familiar with immigration law, its application, and the rigorous assessment processes of UK Visas and Immigration (UKVI), you could run into trouble.
Regrettably, the application process for a UK visa is unforgiving. Failure to supply the correct information and supporting documents typically leads to an instant refusal. This means the loss of the government fees paid (which can run into thousands of pounds) and potentially the loss of your opportunity to come to or remain in the UK.
Given that there are limitations on when you can apply for most visas, it's a high-stakes game to submit an application without first being 100% confident that you’ve met the criteria. First Migrations expertise, knowledge, and excellent service give you this confidence when applying.