Hi Warren
Learning to present, and teach, are certainly useful, but coaching & mentoring are different, in that they are more 'learner-centric'. All under the banner of 'soft skills' which are now recognised as the key to becoming an effective SP. The advantage to you is they are more everyday conversational and not 'stand up in front of people' and be the expert in the room.
You can of course video yourself practising a presentation, just for the fun of it, regardless of any formal course you take. However, I suggest a first step of the 2 day IOSH approved 'Coaching for Safety' course, (advertised in IOSH mag or just google).
Coaching is more about 'conversation' and 'listening', and turning aspects into a gentle questioning line. The techniques are useful in almost every interaction, one-to-ones, groups, even self-coaching. I wish I had learnt more of this in my early years in H&S, although I did have some skills, as it became ‘the way’ for driving instruction in the late 80s.
There is a difference between coaching and mentoring too, but the base skills are similar. The above course covers the continuum from giving 'expert direction' at one end, to encouraging other people to figure out their own answer, or confirm their opinion, at the other.
Confidence in a presentation / classroom setting, combined with coaching skills, can then make you a competent facilitator in workshop-style or action learning events. The focus then is more on getting people learning, (active) not on merely being trained by you (passive).
There is a USA book called 'How to talk so kids will listen', helping parents learn to coach. You may find this useful if you have children, but the principles apply surprisingly well in management too! There is a wealth of coaching books out there, covering models such as GROW, OSCAR and variations thereof, which may give you more insight. My personal favourite is The Solutions Focus by Jackson & McKergow.
PS. Talking fast is not necessarily a bad thing - depends on audience and situation.