Non-competive swim times, and some other questions

Good day Masters Swimmers, I have a few questions regarding swimming and the faithful search engine know as google has deemed this site as very relevant in regards to what I seek! Although the majority of the content here seems to relate to competitve type swimming, my question revolves simply around swimming in general, or in this specific instance, swimming to ensure my own, or someone elses survival. With that said, forgive me if I have posted in the wrong place. I am currently in the hiring process to become a Conservation Warden, and one of the final parts of the process is a swimming test. Obviously Game Wardens are often on the water, and it is very important that they be good swimmers and capable if something were to ever go wrong. The test is not very hard, but none the less, I have started to prepare for it and basically I want to be able to "do it in my sleep" by the time it comes around. The test is to swim 200 yards in under seven minutes and thirty five seconds. A quick search on swim time indicates that this is clearly more than enough time as long as you are somewhat capable of swimming. So about three or four weeks ago I went to the pool and started swimming. I have spent my whole life around water, I am an avid skiier and I own three jet skis, so I would like to think I am a capable swimmer and good at it. I have to tell you...the first time I tried to swim 200 yards all at once...haha, I could barely get 100 yards without feeling completely winded! Needless to say I quickly realized that although the test is not too hard on paper, I did have a little work to do to get prepared. So here I am weeks later and, I know I could go pass the test easily right now, but I plan to keep training so that this is nothing by the time it comes around. Anyways, I was wondering what a good time would be for someone who is not swimming competitively and doesnt plan too? I do not aspire to be able to swim 200 yards in 1:40! At the same time, I don't want to be the slowest guy either. Right now I find I am doing 200 yards in a little over four minutes, and it still feels like a pretty good workout when I finish that last lap, it is by no means "a breeze" but I am too the point where I am swimming 200 yards 3 to 5 times in a workout. Anyways, I went on for quite awhile here...just looking for any insight, feedback, or thoughts you might have on this. Or maybe you could suggest a good workout for becoming very good at swimming 200 yards at a time?