Absolutely! London, Cardiff, and Edinburgh are beautiful and bustling cities each with their unique charm. Here are some travel tips for your trip:

Best Time to Visit:
The most popular time to visit these cities is during the spring (late March to June) and summer (July to August) seasons. September to November can also be rather picturesque, particularly in Edinburgh with the autumn leaves.

Route and Accessibility:
London has several international airports for access. From London, you can take a train or a coach to Cardiff, which takes about 2 hours. Edinburgh is easily accessible via train or flight from both London and Cardiff.

Altitude and Acclimatization:
These cities are at sea level, so altitude is not an issue. However, Edinburgh's old town is hilly and requires some walking.

Accommodation and Booking:
Book accommodations well in advance, especially if you're visiting during the peak tourist season. You can find a range of options from luxury hotels, quaint bed & breakfasts to affordable hostels.

Clothing and Essentials:
The UK's weather can be quite unpredictable. Carry an umbrella and a waterproof jacket. Dress in layers as it can be cool in the morning, warm in the afternoon, and chilly in the evening. Comfortable walking shoes are a must.

Health and Safety:
The UK is generally quite safe. Follow the general safety measures like keeping your belongings secure, being aware of your surroundings, especially in crowded places.

Local Etiquette and Respect:
British people tend to be polite and reserved. Respect queue culture, keep to the left on escalators, and tipping 10-15% in restaurants is standard. In Scotland and Wales, local cultures and traditions differ from that in England and are highly valued. Try to learn a few words in Welsh as locals would really appreciate it.

Moreover, while visiting any of the famous Cathedrals or Churches in these cities, dress modestly out of respect.