dont panic.
we had the same this year. its very easy to get it sprayed by a professional aslong as they can get to the timbers. we have a huge roof space and it cost us £1300 with a 20 guarantee, and took half a day. just make sure you have a "sovereign" guarantee as that covers you even if the company who sprayed go out of business, its a 2 part/paper guarantee approved for mortgages etc. just mentioning this as when we bought our house, it came with a 30 yr guarantee that was basically invalid as it didnt say what was sprayed, with what and how much per sq metre. dont lose your guarantee once you have it as you'l need it if you want to sell.
the worry with woodworm is if the damage is bad, and the timber gets wet, it will absorb water and turn to mush.
the lifecycle for the beasties is 7 yrs so even after spraying, you may still see them flying off, apparently, but they wont lay on your wood again.
hope that helps...some timber specialists websites are very informative.