Some questions regarding bringing fiancee...I know many have asked this but answers seem to differ time to time. I know you are all nice and patient people though

I am a Taiwanese on EP here in Singapore and will stay for years. My fiancee is a British Chinese, an UK citizen. Now we plan to get married next year and I hope to bring her here so we can plan our future together.
Anybody can suggest on what kind of long-term visa she can apply? She only gat a Bachelor so doesn't seem to have good chance for long term social visit visa. If she is on tourist visa, can she extend it to 90-days and leave/enter to get another new visa, or this is not really feasible?
Cheers,
Max