Hi again everyone,
Well, went for a second lesson with the new instructor today, and he said at the start that as the wind was almost calm he wanted to get me to solo today, and that he basically just needed to see me do three good circuits first. So we went up and did a couple, which seemed to go fine, and after the second landing he took control and started slowing us down - at which point I though "gosh, I must be doing something pretty wrong!" but no, he said he was going to let me go up on my own. Woooooo!
He jumped out and I carried on by myself, and all absolutely fine apart from a rain shower that I could see heading my way while on downwind, and that I met just as I was turning base, but I was clear of it again by the time I got set up on final. Landing wasn't the softest I've ever done but it certainly wasn't particularly ropey. On mentioning the rain my instructor said that was why he'd let me out after two circuits because he'd been able to see the rain coming and wanted to give me a chance to go up before it got to us properly!
So very happy today, and thanks to everyone for your advice - clearly changing instructor was just the thing! Actually looking forward to more circuits now I can do them by myself
(Incidentally, although I noticed it climbed slightly quicker without two on board, it didn't seem to feel any different otherwise - quite relieved about that!)