. I would use it for close up of flowers, insects etc
There is more in that than meets the eye.
Generally speaking flowers stay put. This means that a short macro or standard lens with tubes could work fine, or a long focus lens on a tripod because you can take your time.
However...
If you're after insects then trust me you have to be mobile and quick. Forget tripods or fancy lighting set ups.
Anything bigger than 100mm is heavy and difficult to hold steady enough for macro shots with good IQ, unless you have arms like King Kong. To overcome this you will need very good natural light, even with a fast lens, or artificial light. This will mean a good flash, possibly a ringflsh ideally a twin light, but you're talking big bucks here.
yes you can reverse lenses but then you have issues with lens to camera communication. There are ways round this but then gradually the bill adds up.
As far as advice goes I would say get a 100mm macro lens. say a sigma 105. See how you get on with it and if you really like it trade up to something better.
The 180mm canon is a beast, but if you've got the money and are happy to spend it, buy the Canon 100mm macro with IS it is astounding. I am still trying to take pictures that are worthy of it.