Yes, you can switch to a Start-up visa if you meet the visa eligibility criteria, are already in the UK and do not hold one of the following visas:
- a visit visa
- a short-term student visa
- a Parent of a Child Student visa
- a seasonal worker visa
- a domestic worker in a private household visa
- immigration bail
- permission to stay outside the immigration rules, for example on compassionate grounds
To apply to switch to the Start-up visa, you should apply online using the Home Office formĀ here.