I'm a bit south of you and have found this year that the bottom of the grass has stayed quite fresh rather than dying off, probably due to the stop-start growth pattern. I'm planning to mob stock two fields where it's fairly long, get it grazed down hard by the end of August then leave it to grow back over the Autumn. I find the slower growth through Autumn and Winter will give decent quality grazing ready for turnout after lambing, without the risk of grass staggers.