What data should be collected to determine the autocorrelation sequence? For a current project I need to implement an algorithm that needs the autocorrelation sequence of the channel, as part of a key step. 

We're measuring the frequency utilisation in our local area - simply be scanning the spectrum (from 440 MHz to 780MHz) with an SDR and collecting the power at each frequency. The goal of the algorithm is to determine how the spectrum may be split into bands to transmit on.

I want to ask, is this data sufficient for what we need to do or is there anything else we would need to collect?
All you need to do an autocorrelation is a number of evenly spaced samples at a given frequency, so you will need some dwell time at each frequency (which I assume that you are doing already).  That is all you need.