i'm trying to book a hotel for next week, our original choice of Puerto Tahiche no longer have rooms available

we are now looing at El Trebol, but saw on the expedia website that they require a deposit.
""Photo identification and credit card or cash deposit are required upon check-in for incidental charges.""
does anyone know how much they require, we don't have a credit card and cash is tight. we would be booking hallf board. Is this practice common to all hotels in Lanzarote? We have never been asked for a deposit before, but we have always gone package in the past.
Our flights are booked so we have no choice but continue with the holiday. I can't take the risk of the hotel taking all our holiday cash on arrival.
any help please? Many thanks
saffron