I have realised how little I actually knew about UV mapping: this week as been a steep learning curve. Luckily, it will be extremely helpful for future modelling. I now have a much better understanding of breaks, seams, the relax tool and the peel tool. Now I can kind of see if an object will need to be broken up into smaller pieces or can be mapped as a whole.
The objects that took me the longest time to unwrap were the boat and the zeppelin. In retrospect I can see that these objects weren’t that hard. It just took me an extremely long time to remember how to unwrap, work out what technique or tools to use and get used to the new tools.
Now, I also understand when texture seams will be manageable. For example, I have a seam visible on the inside of the boat between the sides and the central strip. However, as I was going to texture that as a separate piece of wood the seam will be unnoticeable.
With the flippers and shields it was much more time efficient to unwrap one of each, delete the others and then just redo all the spacing and symmetry modifiers.
Finally I managed to Tetris them all together. Here is the final UV maps for my model: