While the climate in the UK is not tropical, there are some exotic fruits that can be grown successfully with the right care and in suitable microclimates. Greenhouse cultivation or planting in well-protected, sunny spots can enhance the chances of success. Here are a few examples of exotic fruits that can potentially be grown in the UK:

1. Fig: Figs can be grown successfully in the UK, especially in the southern parts where the climate is milder. There are varieties that are well-suited to the UK climate.

2. Kiwi (Hardy Kiwi): Some kiwi varieties, often referred to as "hardy kiwi" or "baby kiwi," are more suitable for cooler climates. They may be grown successfully in the UK.

3. Peach and Nectarine: Certain peach and nectarine varieties are bred for cooler climates, making them suitable for cultivation in the UK.

4. Apricot: There are cold-hardy apricot varieties that can be grown in the UK, particularly in southern and milder regions.

5. Quince: Quince is a fruit that can be grown in the UK. It has a unique flavor and is often used in preserves and cooking.

6. Medlar: As mentioned earlier, medlar is a fruit that can be grown in the UK and has unique bletting requirements to become edible.

7. Mulberry: Mulberries can be grown in the UK, and they are known for their sweet berries.

8. Pomegranate: In some sheltered and sunny locations, pomegranate trees can be cultivated. They may need protection in colder winters.

9. Vineyard Fruits (Grapes): Grapes can be grown in the UK, especially in vineyards in southern and southeastern regions. There are varieties bred specifically for cooler climates.

10. Raspberry and Blackberry Varieties: While not traditionally considered exotic, certain raspberry and blackberry varieties may offer unique flavors and characteristics.

It's important to consider factors such as soil quality, sunlight exposure, and protection from frost when attempting to grow exotic fruits in the UK. Additionally, local nurseries and gardening experts can provide guidance on specific varieties that are well-suited to the UK climate. Greenhouses or polytunnels can extend the growing season and provide a more controlled environment for some exotic fruit plants.