I will have a stab at this. This should be fine. I think the biggest risk of delay is a delayed first leg, or delay in offloading bags at Heathrow (if checking bags). There is also a risk of a wait at the border, of traffic delay on the M25 and of slow bag drop at Gatwick. I think all of these are more likely to present issues than Gatwick security (where there is fast track known as Premium Gatwick). I would guess though that you would need to have at least three of these factors presenting delays to miss your connecting flight.

One tip if you have checked luggage is if there is a queue at Gatwick premium check-in and only one or two desks open it may be quicker to use the self bag drop machines, especially if you already have boarding passes in hand.

If you were asking about arrivals fast track for non-EU passport holders, I believed this is still closed.