Unsure of exit on roundabout

Ok I know how to indicate on roundabouts has been done on lots of threads but I've a question which I've never seen addressed and am curious to hear opinions on.

There is a roundabout which I often approach from which there are two exits I can take which will lead me home. There isn't much of a difference in distance however one of them has some new horrible mountains of ramps on them so I generally take the other route.

The problem is at rush hour times there can be long tailback on this route and so I put up with the ramps for the sake of not sitting in traffic. However I can't see how much traffic there is on this route until I'm actually on the roundabout.

I approach the roundabout on a single lane which splits into two just as it approaches the roundabout. The left for going left or straight ahead and the right for straight or right. The potential exits are straight, ramps route, right, no ramps but slow at rush hour.

I'd approach in the right lane move onto roundabout and taking my entry as 6 and the exits as 3, 12, and 9, I can see if there will be traffic or not by between 7 and 8 o'clock. At this stage can decide what exit to take and either indicate right or wait til passed first exit and indicate left to go straight ahead.

I kind of know what I'm doing isn't strictly correct however, by the time I know where I am going and indicate it is still early enough that it won't of effected anyone coming onto the roundabout. I'm also in the correct lane for whichever exit I take.

I'm curious to hear the opinions of others on this. What happens when you approach a roundabout and don't know which exit you will be taking, often the signage is just on the exits of roundabout so won't know til on roundabout.