Ye you can. All the hotels and exchange places accept them. M&S do a good rate for levs and also www.travelex.co.uk offer a really good rate comm free. With these you pick your cash up at the airport. Really good service
We've just got back from Borovets and it would appear you're gonna get a better exchange rate out there but they just never change their Boards!! I would just change your money here and be done with it!