Great Run App Training Help

Hi,

I'm new to running and have signed up to do the Great North Run in September, I downloaded the great run app but worry that there's not enough training on it to get me ready for it. I am a complete newbie and can't run for long at all, I'm doing more walking with a little running at the moment. 

Here's the first few schedules:

Week 1 

thurs 15 mins brisk walk & Sunday 20 min brisk walk

week2 

tues 6 x 1 min easy run, 1 min easy walk, thurs 20 min brisk walk, Sunday 6 x 1.5 easy run, 1 min easy walk

week3

tues 30 min easy walk, thurs 4 x 90 sec run, 1 min walk then 4 x 1 min run, 1 min walk, Sunday 20 min brisk walk

I'm on week 2 but have done more than is on the plan as I'm really not very fit!! 

any advice would be great & much appreciated