You certainly can cook @ 200 and I think its the best and easiest may of roasting most joints so that you retain all the juices inside the bird and not in the roasting tin - 3 tips though.

1) Do get a meat thermometer as its important that you do heat the meat through to 180 degrees and most oven thermometers are inaccurate.

2) Put the chicken in a hot oven to kill surface bacteria then after 15mins turn down to 190 - 200. When the chicken is almost done - say 170-175 degrees take it out, crank up your oven to 400. When the oven is hot put the chicken back in (and any veg you want to cook). Take the chicken out after 15mins or so. If you leave the chicken in while the oven is heating up you may find that it all the juices are released before you crisp up the skin

3) Leave chicken to rest covered in foil for up to half an hour whilst the veg are cooking and you are making gravy.

I’ve roasted turkeys at this temperature.
OK its taken 24 hours but its incredibly moist. Lamb is also fantastic done this way ( at 160 degrees) for 5 - 7 hours.

Your “slow roast” is way too cool to start with. Even when I cook on my smoker, the minimal temp is 225 to 250. 200 is barely “poaching” the poor bird.

200 will also probably never get the bird to the required 170-180 degrees of doneness, that temp is simply not high enough above the required finishing temp.

And you also never get crisp skin, you need to be in the 400s to do that, then turn down to the 300s to finish.