Nic, you have a lot against you for any surf on the NE coast of Sri Lanka.
Bring up Google Earth look at the island.
The dominant swells are the same ones which supply the Maldives and Indo . SW, The next factor is the winds Monsoons, seasonal winds and although October is good for A Bay, SW monsoon and definitely offshore on the NE coast, there just will be no surf getting there at all.
That whole coast is a very long Beach break. You would need a local storm and a whole lot of luck! Surf there is rare!
The SE coast in October is winding down to a shoulder season fluky winds and dwindling swell, definitely less crowded because of this smaller but still nice days,
Remember too, the whole NE area has been a fairly recent war zone so awareness and caution might need to be used as well.

I've taken up troll hunting just for fun, instead of a rifle I'll just use a pun! 冲浪爷爷