The descents aren't ususally the problem. On the Bus you can easily put conditional height constraints - at or below/at or above in the FMC provided they are put on the plate for initial planning consideration. There are ommissions into LGW and MAN at present. DUB/LON want 290 by LIFFY usually and LON want 270 by GIBSO. They are not on the initial planning box on the appropriate charts and should be as we can modify the descent profile to make the whole affair more efficient.
The big problem is still the climb constraints out of MAN. Most Airbus types that are going a fair distance cannot make 310 - 50 before MID - it just ain't going to happen unless you squander all your energy and then you will have a level acceleration for the next 20 miles. My tack now is to be ready with a best guess at a steady climb speed, say 280kts and when cleared, advise our best possible level. If I need to vector or level, I would rather that than struggle up. A better level would be 280 - that would be achievable nearly all the time.