So after my recent mini crisis of confidence in the sewing field, I took a deep breath and just got down to it. I think part of it is just accepting that it's a learning process and that there are going to (possibly, likely) be a few iterations.
I laid out my front side pattern piece and cut into it, lowering the bust apex, spreading the pattern piece out, closing the resulting dart, inserting extra tissue paper and taping it all together. It was, like most things when you follow the directions, easy.
Then yesterday evening I cut out the front, back and side pieces from calico and stitched it up. It was a bust (pardon the pun but was one ever more apposite?) Didn't fit - I had lowered the bust apex too far and hadn't added enough in the bust and will have to start over again. BUT, even with these shortcomings, I saw the shape of things to come, a top that is going to fit me. As soon as I get a free half hour or so (which really, is as long as it takes to do the fba as per the instructions that come with the pattern) I'll give it another shot.
And I'm delighted that I didn't even cut into or waste a shred of my super-cute fabric, upcycled from a French Connection blouse purchased second hand.