Direct Train from London to Hastings

Both-

Trains from Victoria are every hour, and take 2 hours. They have a final destination of Ore (a suburb of Hastings one stop beyond) on the line to Rye. Advance, train specific fares start at £7.

Trains from Charing Cross run twice an hour, terminate at Hastings and take 1 hour 30 or 1 hour 45 depending on stopping pattern. Advance, train specific fares start at around £13.

Use the journey planner on the National Rail site to find train routes in the UK.
https://www.nationalrail.co.uk/
When you aren’t sure which station, select ”London (All Stations)”. National Rail shows direct trains from both Charing Cross (on Southeastern) and Victoria (on Southern).