"Take what is useful and discard the rest".
I find this being said a lot about IAM courses - They teach some good stuff... but some of it is useless bollocks that does more harm than good. There are some members who are great, both as riders and as people. They tend to be the kind who take only what is useful.
Unfortunately, most IAMs I've met are elitist wankers, who think holding an IAM pass is all about going as fast as you can and riding like a fucking dickhead. Most had 6 points or more on their licence and there seemed to be at least one accident every time they went out for an organised ride.
The worst of them I ever knew spent an hour trying to get his knee down on a roundabout, instead of conducting my DAS course like I'd paid him to!!
I also had one IAM twat seriously cut me up, back when I was new to my Club at the time. He actually clipped my right mirror because he was "high speed passing" that close to me.
By contrast, I've only ever heard good things said about BikeSafe days and the ROSPA members have a better rep.
But before you start anything advanced, you'll need a firm grounding in the basics and riding experience, if for no other reason than knowing what is useful when you're taught it.
A bigger bike would definitely be an advantage, but even then get a decent amount of riding time in on that before you look to the advanced side.
Meanwhile, something you can do to improve your riding right now is read.
Specifically, 'Roadcraft: The Police Riders Handbook' and perhaps also A Twist Of The Wrist (vols I and II). I personally didn't like the latter as it seemed too full-on racetrack riding science from the outset, but Roadcraft regularly gets a read from me!!