To me, the main reason the Brit Sniper is so underutilised is that it comes too late. It often comes onto the field facing an Ost Sniper and 222 already built. But simply putting it at T0 would make it the cheapest sniper in the game and probably too punishing.
It comes out in just under 140 seconds if you rush it. The AT sniper is the third unit.
Ostheer can do it in just under 60 if they build the sniper as their second unit. But that's just a Pioneer and a Sniper. No Grenadiers, no HMG, nothing.
Ostheer does it in just under 100 seconds if they build an HMG first. The Sniper is the third unit.
I'm pretty sure you could close the timing gap between those two by letting the UKF sniper get in the UC. I'm actually not sure why it can't already: it's a closed halftrack mechanically, and snipers can enter other closed halftracks.