It wouldnt surprise me if I was confusing you as I'm confused myself. I've spent several more hours with it and its slowly coming together. I did play with showing border edges to see if that was the problem/cure, so maybe that confused what I was saying. I have been using shaded shells since and I find this helps too. I think I was confused because when I was deselecting objects/geometry, it was disappearing from the uv editor, and to my uneducated mind that meant that any work I had done to that shell had gone with it, whereas I've since realised reselecting that object brings back the shell in its last place, and I've got used to the whole method of selecting, reselecting, and working in both the workspace and the uv editor at the same time. I took several useful tips from the free texturing tutorial yesterday for use in photoshop, and i have just completed my first texture I was happy with, that there wasnt such an amount of trial and error about. Hope to post pics over next few days.
Thankyou to everybody for your help.