switching from student visa to Entrepreneur visa

I have been in the UK for the last 3.5 years doing a PhD on a Tier 4 General Student visa, but I am thinking of quitting/suspending the degree. If I do so, my student visa will become invalid, and I won't get any qualification.

I have also been in the UK since 2003 on student visas continuously and successfully obtained my undergraduate and master degrees.

The questions are:

1. Can I switch from this to a Tier 1 (Entrepreneur) Visa?
2. Can I apply from within the UK?

Many thanks for your help,

Derrick

Switching is applying from within the UK.

Yes (245DD).