Switching between London Marathon Advanced Training & the Improver Training Plan

Pipski

Hi 
I need a bit of advice.   I have the London Marathon on 4th October.  I've only ran one marathon but in 2014.  Back then I overtrained and then went into the race a bit under trained with shin splints (but my physio helped me manage that).    I walked a lot from mile 18 but I finished in 4:036.  Fast forward to now (I'm 50 the day before the race) less fit but I am still training a lot.  My question: Is it ok to follow the advanced training programme but not to incorporate the fartlek runs? I'm scared of getting injured again.  I often look at the Improver plan and think I am running so much more than that.   I don't want to overthink it all as the last time I became obsessed.  I think back then I wrote on this forum every day about it!   I am currently running 5 days a week with some weight training inbetween.   Last week I ran 37 miles and my easy run was 10.5 miles.  On a Wednesday I go to a running club but I struggle to maintain their 9mm for 6 miles.  I'm around 9:30mm.  I am getting fitter but it's taking longer to get there.   Any advice would be fab.  Thanks