Cirrus
Veteran
What training plan are you following? I’m doing Manchester too and don’t routinely run 24k for a couple more weeks.
The intermediate HR based plan from Garmin. Did it on a previous marathon and it worked well for me. Long slow runs are time based rather than distance, last week's LSR was supposed to be 2hr 15 (misjudged it a bit so I ended up doing more distance and time than I should have) this week’s only 1hr 30. So it varies, then there are a couple of interval sessions/fartleks and slow runs during the week.
I’ll also start some core strength work and incorporate some hill work as I’m tempted to either do an ultra (only a 50k) or some trail runs e.g. https://www.runthroughtrails.com/tittesworth-water/ after Manchester