Last year in Spain we were charged 6% for cashing our Euro travellers cheques, having been charged zilch the year before in Corsica.
What's it like in Carvoeiro?
Where's the best place to exchange?
Or should we try to stick to plastic?

Best stick to a debit card and get money out of the ATMs bank charges can be high for cashing cheques

I wouldn't recommend bringing travellers cheques, the commission is quite high. ATM cards are much better and cheaper, there are several in the village plus one at intermarche - just be careful not to run short at weekends and public holidays as the machines do tend to run out quickly

In the bank the other day I overheard someone changing cash into euros and I think they said the charge was 8 euros whatever the amount