Hi Kicker,
I´m Spanish. I live in Málaga town.
Many places in the province could fit your needs, but we would need to know more clearly about this:
1- The temperature is not the same in all the province. While staying 15 kms inland can be very hot in summer, on the coast can be quite fine, especially in the evenings. Even depending on which coastal area you stay, climate may be better or worse (I talk about "too hot" in summer.
2- You like Spanish or British area? I mean, do you want to be near british amenities, bars, etc. or you want to be away from it? There are interesting places where you can have both, which may be convenient. You are in "Spain" but in 15 minutes drive you can related with british community and services.
3- Choose be near to an important international airport, like Málaga airport, for instance. Come what may with low cost airlines in the future, an important airport will always give you choice for sure of a conection with the U.K
4- If you have Spanish friends or British friends already living here who understand Spanish, they can help you search in local internet real estate sites, ads of properties for sale directly by the owner (Spanish or British). You can find very interesting prices if you look for properly. Is better than going to any Spanish or British real estate company. Then to feel secure, ask legal advice (Spanish or British), there are good and bad ones in both cases, like in everything :-)
As a general rule, you´ll find the western coast of the province more "over-developped" but with more services and the other wayround on the eastern coast and inland, but this can vary looking more specifically by towns. All together, following the conditions you say you need, I would consider areas from Calahonda in the west to Nerja in the East and the area of Valle del Guadalhorce, which is nice, well connected and to a certain degree, still unspoilt.
Good luck