Training plan for sprint (8 weeks)?

I'll be participating in a sprint in 8 weeks. I've done a couple before but never been fully happy with my performance. I've tried looking up functional training plans (using a Suunto Ambit3 so have been looking at the plans on their site) but I'm very unsure of which one to choose. Any advice?

Some facts - I'm in reasonable shape (but could definitely be better), 42y, hoping to finish somewhere in the 1h10min-1h15min range, which would be a PB. I have other commitments - family, own company - so time to train is a bit of an issue.

Thanks!