How to change UK visa to UK Startup Visa?
You might be able to apply to change (‘switch’) to a Start-up visa if you’re already in the UK on a different type of visa. Your partner or children will need to apply separately to switch their visa. They can either apply at the same time as you, or at any time before their current visa expires.
Who can not change his visa?
You cannot switch to this visa if you have one of the following:
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