Posted: 28/05/2014 at 14:52
Clare, there is no doubt that running more miles per week (sensibly) would help you improve the time but with limiting running time available you would probably gain more by doing one of your runs faster. If you can't join a club, there are, as has been said, plenty of published training plans. Most of them assume that you have plenty of training times available so you will need to customise to suit. Generally, running less than the plan suggests will not cause too much of an issue, but be wary of trying to make up the deficit by running too hard or too fast - it may work for some, but most of us just end up knackered and fed up. In my opinion, some sort of threshold type work will be the most valuable for you now you have the basic endurance to go the distance.