South facing steep bank

Hello

We have a South facing garden of about 1 acre which is roughly a square with the house top left of centre but the back garden is on a slope. We have thought of putting two banks in curving round to the right side of the house with lawn areas. We cannot afford retaining walls and the banks will be between 1.2 and 2m in height. Can you suggest what ground cover we should use in these banks, they are fairly long (around 50m each so I would imagine wedding would be extensive! Also what should we do at the top of the bank where it meets the grass of the terrace above?

Any ideas would be really appreciated.

Purita2