The itinerary lasts 12hrs 48min, and has 2 steps.

London - Paris
The step from London to Paris lasts 2hrs 18min. You'll travel in a Eurostar.

Paris - Ax-les-Thermes
The step from Paris to Ax-les-Thermes lasts 10hrs 30min. You'll travel in a INTERCITÉS de nuit operated by SNCF Voyageurs.