Kate
If you do three big sessions a week - long run, speedwork, tempo then you could probably just about get away with it but the more you do the easier it will be and the faster you will get.
However doing alll the sessions and doing lots else means you will just get tired and probably injured
The hockey probably helps but not sure about the riding!
It's difficult when you have a busy life and lots of alternatives but it may be best if you can to put some of those activities to one aside until after the marathon. Once the marathon is over you will probably want a rest from running and will enjoy the riding etc more!
EP
You do the speedwork because it's on the schedule and have to set an example!
The more speedwork you do, hopefully youu will get faster and apart from running quicker times at shorter distances which is great in itself, adds a pyschological boost, it also means you feel more comfortable running a slower pace at marathons.