Snuffy I grow all year round in the polytunnel. From memory last summer I grew tomatoes, cucumbers, courgettes, sweetcorn, all salads stuff (lettuce onions etc), herbs, peas, french beans, runner beans and broad beans, strawberries and hanging baskets of tomatoes and nasturtiums. Later in the summer i put in leeks and chard and these have been growing all winter along with some winter lettuce, garlic and onions. Hopefully these will all be harvested before I need to dig in more "stuff" and get planting again. It is also a great place to overwinter perennials going cheap at the end of the season adn any shrub cuttings that you've taken. I also kept my Christmas tatties in their pots before harvesting.
Hope this helps
Jennie