Has any ever set up. Point to point wifi bridge , my own house I can't get fixed line broadband , but my parents house is about 2.5k away , with a line of site , it's vodafone they have , so what frequency antenna would I need ?
You could use two NanoStation Loco M2 Directional Antennas to do this. Here is a link to them on Amazon:
The range of these is 5km with a clear line of sight, so this should work for you. After you configure them to connect to one another place one on each building, pointing at each other. The antennas connect up to a Router with an Ethernet cable. You'll need another Router in your house as well.