Thank you so much, you've been extremely helpful. Wasn't expecting a video!

I didn't realise that you could fix the 'bridge' operation with offset, I was doing every other one manually and then using 'fill hole'

Just another question, on this particular model I haven't been modelling with smooth mesh because I was concerned the poly count would be too high, since there are lots of little pieces. I've modelled smooth mesh before, and then done smooth mesh preview -> polygons so that I can 3D print or render. Is it better to switch between smooth mesh preview to check the model and is it better to model, and carry out the conversion, is there a way to keep the polys low in that conversion?