Eating locally produced seasonal food is a great idea Sarah. By eating locally produced food you'll be reducing the carbon footprint and supporting local producers as part of a circular and more sustainable economy.
Non-seasonal food is, as Jon mentioned, more problematic, it requires either more transport or more heating but if the producer is using bio-gas or solar heating for example then it's much less of an issue.
Eating locally produced seasonal food what people did prior to the globalisation of supply chains and is inherently more sustainable. I have found it interesting and challenging to develop recipes based on local seasonal vegetables, nuts, berries and herbs.