Competing against yourself and seeking an improvement every time you shoot, is going to be one of those holy grail missions. I think you will have times when all goes well and your shooting is on form, then there will be a time when perfect accuracy seems more elusive than ever. That has been my experience, in outdoor comps such as FT and HFT, and indoor comps such as LSR and bench rest.
If anything, I find bench rest the most frustrating of all. The margin for error is minute, and the search is for the best match of pellet to barrel, along with best pellet consistency. In other words, the input you can make with improved technique won't help your scores; it will be down to the kind manufacturers of the pellets to deliver a consistent product, and the equally kind manufacturers of the rifles to supply one with the least variation from shot to shot.
In the HW100 you do have a rifle that is more than capable of doing the business. One of the best LSR shots down here uses one and regularly brings home the trophies. Optically the T35 is a superb scope, and why they are so cheap - relatively - is a mystery.
Searching for those technical improvements is something that many of us do. In competing against your past performance you don't have a yardstick of comparison with others, and it may be that in your part of Wales there aren't too many opportunities for shoulder-to-shoulder comps. We have the same situation in this part of Devon, with very low population density, and the answer is to take part in some postal competitions. That will give you a good measure of how well you are doing. For example, you could shoot bench rest in the Devon County league; you don't need to be resident here. The princely sum of £6 will buy you an entry this winter season, including enough target cards.