Thanks Sadie and Corsair for your help - it's really appreciated.
I think I'm just going to have to practice, practice, practice - become a clipless newbie all over again! I'll try a bit in a quiet road - before launching myself at the mercy of the traffic!
Just when you think you cracked the whole clipless kerfuffle, you have to start from the beginning all over again! That's why I love cycling - always something new to learn! Well, that's not the only reason - but you get the gist!
I'm going to have to train my brain to push down and pull up with the right leg, and then engage the left (so, as you say, it's at the bottom of the pedal stroke). I have been trying to do the one-legged rotation thing, and letting the left coast until it's at the bottom to clip in, but it's a bit perilous in heavy traffic and on hills!
Corsair - I do tend to clip in while seated - unless I'm planning a quick getaway, but wouldn't try that in my road shoes just yet (a graceful getaway would be a bonus!).
I'm also going to think about changing my pedal/cleat system, to go for a bigger platform - and save the mtb shoes/pedals/cleats for my commuting bike. Yay - justifiable reason to hang round the LBS! Won't be changing for a few months yet though, not until I return back home to the UK in the summer, due to severe cash shortage - but gives me 6 months of research - pondering those age old questions - which cleats and shoes to get!!
Thanks again for your advice - it's been a great help and much welcome!