Last piece now being printed..
I'd better give the poor thing a rest for a few days...
91 hours printing time.....
Hope it goes together

I'd have been finished but for our morning jaunt..
Delivery tonight.
The answer -
- General Rule:
Layer height should be a percentage of the nozzle diameter, not exceeding 80%.
- Example:
With a 0.4mm nozzle, a layer height between 0.1mm and 0.32mm is generally considered optimal.
- Layer Height vs. Print Speed:
Thinner layers (lower height) result in more detailed prints but take longer to print due to the increased number of layers required.
- Layer Height vs. Print Quality:
Thicker layers (higher height) can lead to visible layer lines and may sacrifice surface finish, but they print faster.
- Nozzle Size Impact:
Smaller nozzles allow for finer details and thinner layers, while larger nozzles allow for faster prints with thicker layers.
- Material and Print Type:
Consider the material and the desired print type when choosing layer height. For example, you might use thinner layers for intricate details or larger prints, depending on your priorities.
In essence, the relationship between layer height and nozzle diameter is a trade-off between print time, resolution, and print quality. Choosing the right balance depends on the specific requirements of your project..(off Google)
Nozzle size is generally .4
I'll not bother printing as that answers my own question