Here are the completed sentences:

1. Lan hasn’t decided where to go on holiday. **MINDED**
- Lan hasn't **minded** about where to go on holiday.

2. We don’t like travelling during peak season. **INTO**
- We are not **into** travelling during peak season.

3. Scuba-diving is not really my cup of tea. **INTERESTED**
- I am not **interested in** scuba-diving.

4. No mountains in Western Europe are higher than Mount Blanc. **THE**
- Mount Blanc **is the** highest in Western Europe.

5. They require special permits to access Son Doong Cave. **TO**
- Special permits are required **to access** Son Doong Cave.