Dont bother with travellers cheques Lynne. You can atke Levs I do now if you can get a good exchange rate of 2.7 or above. Sterling is fine and easy to change up. Make sure that your note are new no rips or writing on them and not scottish. Also only change at you hotel recetion/Bank/Post office. Do not be tempted by the boothes you may see offering a good rate. These are a con.
I changed steling at the booths near the Rila with no problems. Best way is to change in multiples of ten and ask how much you will get before handing over any money. Uts easy to work it out that way. Enjoy your trip.
Regards
Jay