Sure! Here's what you need to know for your trip to London, Paris and Rome.

Best Time to Visit:
The best time to travel is in the spring (April-June) or fall (September-November), when there's milder weather, fewer tourists and lower prices. In summer, these cities can get quite crowded with tourists.

Route and Accessibility:
Your route will depend on your starting point, but if you're starting from London, it's easy to get to Paris via the Eurostar train, which takes around 2-2.5 hours. From Paris, you can take a direct flight or a train to Rome.

Altitude and Acclimatization:
These cities are not at a high altitude, so acclimatization is not a concern.

Accommodation and Booking:
It's recommended to book accommodations well in advance, especially for the high tourist season. All three cities have a range of options, from luxury hotels to budget-friendly hostels.

Clothing and Essentials:
Wear comfortable shoes as you'll be doing a lot of walking. Pack an umbrella or rain jacket, as there can be sudden showers. Also, pack a travel adapter for your devices, as the plug type is different in Europe.

Health and Safety:
Stay updated with the local rules and advisories related to health (like COVID-19). Keep your belongings secure and beware of pickpockets, especially in crowded tourist areas.

Local Etiquette and Respect:
Europeans appreciate politeness. Learn a few words in the local languages, like 'please' and 'thank you'. Respect local customs and traditions. When visiting religious sites, ensure that you dress modestly.