respectable family want to rent up to £850 PCM whats emersons green like ? downend, horfield, filton abbey wood, stapelton these are some of the places coming up on house searches . we have 3 children and want to feel safe and happy.

They are all nice areas, i have family that live in Stapleton. The real down side though is that you are pretty much surrounded by main roads, and traffic can be complete hell around north bristol/south glouc, as you are right next to the M5, M32, M4, but of course, this also means you have easy access to these motorways as well for commuting etc.
Finding somewhere nice to rent for the money you have should be easy.
You could also look at North Somerset maybe if you wanted somewhere a little quieter, but still near the M5 and with 3 bed houses been rented form about £600 a month.