With the bass spawning or about to, will they go all the way to the back of a creek or will they stop along the way to spawn if there is a flat or such? Thanks

There's no definitive answer because conditions, tide, structure, bottom content, current, water clarity, and temperature all come into play. Identify a few of each during your preliminary map study, and go test the waters. It's one of those things that only time behind the bait will tell. In theory, no wildlife (deer, bass, or otherwise) will travel any further than they have to in order to execute the survival function, whether fleeing, feeding, resting, or spawning. In other words, if they bypass the flat to get to the back of the creek, there's some preferable circumstance(s), listed above, that puts them there. If you can find out what that condition is, you can try to replicate it elsewhere on the lake. Either you can replicate it or many lakes (I am learning) are big enough to where they could be multiple patterns happening.