Moving to Dubai 90 days visa

hello,
i am looking for a little bit help. I want to relocate to Dubai from UK but I am little confused with visa situation. I alway went to Dubai with 30 days visa but now I am reading about 90 days. It will be less stressful for me as I will come to Dubai without job as its impossible to find something from here.
I was wondering, if someone here has more info... can i request this visa on arrival or will I have to apply in advance for fee? or is there any formal website?

I am looking forward to hearing from you :) Thank you so much

Lenka