October off-season. Still the season (ending) in the east, Trincomalee, Nilaveli, Pasikuda. You can also go to the south, to Unawatunu. Unavatuna is cheaper, and there is somewhere to go in the evening. Trincomale is more expensive, and in the evenings boring. As for the excursion, in Sri Lanka they mean moving. So book a tour for 3-5 days Look, I wrote recommendations for planning the rest. I think this will help you make the right decision.