I'm surprised no one has mentioned take-off flap settings. Most of the aircraft I have flown are quite happy taking off from a hard runway without any flap but I would recommend using flaps for take off on grass. See individual aircraft flight manuals for recommendations.
I would treat every grass runway as performance limited (for take off & landing) due to the number of variables. Ie length of grass, moisture level, firmness of surface etc.
By the way I wouldn't recommend either Netherthorpe or Derby for a first visit to grass. They are bith just a bit short for comfort. Try somewhere like Hucknall, or Sywell.