British citizen, residing in Prishtina, wants to apply for tourist visa.

You can't apply online. Someone else can also apply on your behalf. Copy of flight tickets booking is ok if you don't want to buy a flight first. Detailed travel itinerary and hotel bookings are required for tourist L application. If you can't provide them, you can try to apply visa without them, but your application maybe denied.

You are a British citizen residing in prishtina, you also should provide the original and a copy of the residence permit, work permit or Serbian ID card which should be valid for at least six months.