From reports, you may be able to get away with a 1.45m dish, but a 1.8 or 2.4m dish would be best if space and budget allows.
BBC and ITV and C4s are all available for free and without a sky card, so any reeciver box should do, be it Freesat, Freesat HD, Sky, Sky Plus, Sky HD or Generic.
Note that some channels even on the big dishes may not be available all day, especially BBC2 and FIVE.
However, if you have a SKy receiver and a sky card you can access stronger versions of ITV, C4, Five, and also have access to Fiver and Five USA, and Sky three - the last 3 are not free to air, but free to view, and are not available on Freesat receivers.
There are many companies inthat area, many have been mentioned on here before:
lee-digital.com, a2sat.com,televisiontechnology.eu
I actually think Freesat Murcia (Dave) actually lives in Javia, although covers that area also.