A couple of years ago I retired from a life time of earning a crust firstly by repairing motorcycles and then the last 22 years by teaching in a FE college engineering department. One of my responsibilities there was to set up a motorcycle repair and maintenance course for students intending to go on to find apprenticeships. So I write with some experience.
First, I would think about the time left before you depart on your intended trip and consider what you skills can realistically manage to master. It takes a long time for a novice to learn the underpinning knowledge and master the skills necessary to become competent. So unless you are looking at taking your trip some years in the future, I would say it would probably be better just to learn some essential skills before you go. For example tyre changing (there is a good HORIZONS video that deals with this), puncture repair, how to adjust and replace a drive chain, how to replace brake shoes and / or pads and other simple maintenance and repairs.
Get hold of either a Haynes or Clymer manual for your bike and have a go. Use the manual and start with the simple stuff. Chain adjustment, topping up fluids, replacing bulbs etc and build your confidence. Then move on to practicing removing the wheels, start with the front since it is usually easier. Then you can progress to other more difficult tasks. It's all PRACTICE, PRACTICE, as far as dismantling, reassembly and maintenance is concerned.
Where the real skill comes in is being able to make a diagnosis and that will come from understanding how the various systems work and the experience you have already gleaned. To help you understand how systems work you could look at the various tech books published by Haynes and a book published by Pearson called Motorcycle Maintenance and Repair, which is for work based learning courses but it will give a useful insight into understanding motorcycles.
Above all don't be afraid to have a go. You will inevitably make mistakes, but a few mistake made before you go should result in less on the road.
I hope the advice is helpful, but do ask on this forum if you are stuck. I have no experience of modern Triumphs, but there are plenty of knowledgable folk around always willing to assist.