Dublin 2019 from scratch

Hi,
 I am determined to run a marathon this year. I have been running off and on for a good few years now. I have completed 2 half's although the last one was 5 years ago now. I haven't done any running in over a year. I am signing up to Dublin (Oct 19) and i am starting back running this week. I understand it will be a major undertaken and i am not taking it lightly.

Looking for advice. I am currently 41 year old male, 5ft 11 and 15.5 Stone. I understand i need to drop weight and have changed my diet in the last few weeks and lost 0.5 Stone.  Apart from that i am healthy.

My plan is to do the couch to 10K that will bring me up to the middle of march. I plan on upping the to a half marathon distance by end of June and then be ready for the Marathon in October. Is this doable? 

Would people recommend a different strategy?

Thanks