Eurostar from Dover to Disneyland? Doesn't Exist—Disneyland Is in California

Eurostar runs London–Paris/Brussels/Amsterdam via Channel Tunnel. It does not serve Dover (ferry port) or any Disneyland.

• Disneyland Paris: Take Eurostar to Marne-la-Vallée–Chessy station (gate of park), ~2h45m from London St Pancras.
• Disneyland Resort (Anaheim, California): Requires transatlantic flight + transfer; no train from UK.

If you meant Disneyland Paris, book Eurostar direct to the park. If you meant California, fly LAX/SNA/ONT.