I am in complete agreement with you on this one. The mere thought on of an encounter with a rat leaves me shuddering!
Fortunately I have a solution in the form of a Pest Stop device. We have a problem with mice in the greenhouse at the Kitchen Garden and installed one of these about 6 weeks ago. We have not seen one mouse since it was installed and were previously catching around 5 a week!
On the strength of this success we have just installed an Outdoor Pest Stop as rabbits have been sneaking in and nibbling on our figs.
Good luck with starting your organic garden. If you have any other queries about any aspect of your garden, please don't hesitate to contact me again.