I was in Mojacar 2 years ago in August and really in comparison to Benidorm and Costa Del Sol it is very quiet. There is no real area like a strip that is full of bars and clubs. Mojacar Playa is very long and spread out and you will have no trouble with noise etc. Do you know which end of the Playa the Apartment is at. I would reckon the noisiest area in near the Pueblo Indalo complex. Hope this helps.

"50m from the beach in the heart of Mojacar Playa".

Difficult that one as the Playa is about 7KM long and if the heart was the middle then I suppose this apartment would be somewhere near to the Commercial Centre roundabout at the bottom of the Pueblo road but I suspect by heart they mean somewhere between the Pueblo Indalo and the Indalo Hotel.
As already said dont worry about Benidorm you couldnt be further away although of course there are a few Brit owned bars and restaurants if thats what you mean.There is little noise from these bars.

Last year the last week of July and first three weeks of August were very busy,at least on the Playa road but of course if its busy then the vehicles are going very slowly and you wont hear them anyway.

If you can find out exactly where this apartment is situated we can help more,I'm sure you will have a good holiday as long as your apartment is nice how can it possibly go wrong

John.