Bulgaria is included in europe on every site i checked. If your worried then just read the terms and conditions or FAQ. It's normally listed what countrys are included in each category.
I've said it before so i'll keep it brief and not bore you, Big ski party last year, sister broke leg, Tesco insurance were RUBBISH, Almost a year on, they still messing her about, Stay clear. Get the best you can not the lowest price, The doctor at pamps told us she thought the post office was best, Is that from the horses mouth or wot!
That is interesting i would have thought Tesco would be good. I just hope don't need to use it ever. Make sure you take precautions and make sure your in good enough shape for the rigors of skiing/boarding. I got mine with fogginsure this year. Little bit more worried this year because might be using some non-releasable skiboard bindings. Best bet is be smart, don't push yourself to hard, don't take stupid risks. Hope nobody gets hurt this season.
I got our insurance from www.free-spirit.com as they do online medical screening, because of asthma some places would not cover us for winter sports. Didn't need to claim though so not sure how good they are, policy wording was the same as any main insurance and price was pretty reasonable.
Might be worth contacting Egg, especially if you already are a customer. I got annual multi-trip for the whole family for Europe including 17 days Winter Sports for £15. It was a special offer, but I've seen them do it more than once. I also found their customer service to be excellent (when I had a transaction dispute with Time Computers ,.....not had to make an insurance claim yet....)