the AT tommies frankly suck. Even before the PIAT turn into heat seeker the BOY rifle were barely adequate.
All this obsession with the AT nade is distracting from the fact the british's current kit isn't that great after all the nerfs they have taken. Firefly extremely high cost, Comet underwhelming, PIAT underwhelming, Gammon bomb impractical, cromwell underwhelm.
Adding the Snare isn't going to suddenly fix the British. We need to look at what's already available to the british and identify their weak links.
The AT tommies become quite obsolete after medium tanks hit the field, yes. Against light vehicles they work just fine (essentially a stopgap unit). If they were buffed to be very potent then everyone would get Tank Hunter IS and nobody in the right mind would pick up PIATs.
In my mind, you would go for 1 IS with Boys to serve as stopgap AT in the early/mid-game, unlock weapon racks and mix Boys IS with PIAT-wielding Sappers later on.
It's probably true that providing Brits with a non-doctrinal snare would not be the magic touch needed to make this faction viable again. However, it does solve the problem of Brits not having a proper snare (while every other faction has it). Giving a non-doctrinal snare to the Brits would also make them more viable than they are now.
Buffing other aspects of the Brits might be outside the scope of this thread.