It sounds like you're already running around 10k (60 minutes quite slowly), so I'd try to build to a ten miler by October/early November, and then as suggested above a half by the end of the year/Jan.
That's a good base to come off for an April marathon.
Essentially just build up gradually (not more than 10% increase per week total), do a long run at least once a week. It sounds like you're currently doing about 6 miles max, so build this to 7, then 8 etc, plus lengthen other runs as well. That's a fairly easy way to get to a ten mile over the next six or eight weeks.
Basically take the same approach to build to a half.
HTH, Iain