Hi there,
I have just come back from Costa Teguise last Monday and the exchange rate was 1.22 - although a little bar/restaurant called 'Popeyes' ( in Las Cucharas shopping centre) had an exchange rate of 1.25

This was from 25th August - 8th September so not sure what it will be this week?
Anything over there will be better than the exchange rate in the UK at the moment though!! I'm sure it was down to 1.15 when i looked through the week!

I would change over there if i were you.
Have a great holiday