I'll try my best to give a valuable advice malli,
If I were you, Iwould enter the local Uni, My background is not Engineering, hence I cant tell you what to take up. In my opinion, best thing to enter Katubedda Uni, take up some apprenticeship relevant to the field chosen (if such a thing available in SL), complete your degree, then come to Australia for your Masters/PhD........
On second thought, due to the prevailing situation of the country, coming to Aus may be a better choice, if your old man would not struggle to send you here (that is if your family is really well off) you can take up that path, come here do studies, do bit of work, so you woudnt burden your parents, you can have fun, no fear of bombs, no disheartening unjust, unfair things, no strikes, no close downs.....you'd finish your first degree in max 3 years..........opportunities are sky high here.
I still have a soft spot for SL university system, after all, I'm here today thanks to that, you should ask someone like X-pert too, they have experience in Uni education of Australia.
Whatever, too things;
Hardwork Pays...........Ugathamana silpayamai mathu rakena............
Focus, go for it...........enjoy the life, go for the goal...........
Good Luck Bro.....hope this help at least a little