Hi Fat Gaz,
There is a specific 'sticky' thread for currency questions
HERE.
Was wondering what is a 'good' exchange rate for the Lev?
It depends when, as the rate changes daily in line with international currency market fluctuations.
Today, as of the time of writing, HSBC online is offering £1=2.872619 Leva - which is higher than the National Bank rate in Bulgaria.
Is there a limit on how much Levs you can take into Bulgaria?
Up to 8,000 Leva or the equivalent in other currencies without a Customs declaration and up to 25,000 with a declaration - but you can take virtually any amount above this with permission from the BG authorities.