To be frank, you will be better off driving to Playa Lisa in Santa Pola , it has some disabled parking and you park right behind the beach which is flat and about 25M from the water. It is mainly a Spanish Locals beach and pay sun beds are very rare, but you can buy your own to take from the Chinese shops which will save you money in the long run.
The Carrabasi beaches have no disabled parking areas near them, the carpark by beach 1 has a steep uphill then down hill walk to the beach of probably 3-400 metres, beaches 2/3 and all the way into Los Arenales only have street parking and fairly long walks to the beach down wooden walkways.
On the subject of disabled bays, most of the ones I've seen locally appear to be an afterthought, and make driving into them more difficult than a normal parking bay, they certainly don't give you any extra room for opening doors or manoeuvring wheelchairs.
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