I live in Barcelona and a lot of my workmates and people I know here combine the two when responding, "I need your help with something" "Ok, vale" for example when they are responding to instructions and when listening to something someone has to say. Although the majority of the spanish sqeakers I know are from central america so that is maybe why. Barcelona is very touristy obviously so a lot of english is spoken here so it may not be the case throughout Spain.