Hello and congratulations on your upcoming wedding!
Barcelona is an excellent choice to visit with great food, architecture, shopping and the Mediterranean right there. There are beaches near Barcelona (in Barcelona as well, but much nicer outside the city) traveling north up the Costa Brava or south down the Costa Dorada.
However, if you want to go to Andalucia, that is also an excellent option both for beaches and cultural sights. It will be very hot that time of year, but since you are from Egypt, it probably won't feel too hot for you ... Personally, I like the beaches along the coast of Cadiz (this is Atlantic Ocean side) very much as they are less crowded with tourists and you get more of the flavor or Spain - some examples are Bolonia, Zahara de los Atunes, Canos de Meca and Tarifa. If you decide to go here, I would suggest flying into Jerez from Barcelona, or you could also look at Sevilla to fly into, and renting a car. However, the beaches along the Mediterranean side have the prettier turquoise colored water, even if they are more crowded with tourists. For this, I would suggest flying into Malaga - there are cheap flights -- or if you want to see Sevilla, into Sevilla. Depending on what beach, you could get there by bus or train from Malaga, or else rent a car. One other thing to mention is that you might want to see the Alhambra in Granada. It's quite spectacular. If you do that, you could look at flying into Granada.

There is train service between cities as well, but from Barcelona to Andalucia is fairly far, and you'd have to change trains in Madrid.
I'd suggest spending 4-5 days in Barcelona and then the rest of the time in Andalucia. Have a great time!