West Byfleet, on the curved bit of Platform 3, can be quite nasty.
As gaps go its quite large, especially vertically, but not a record breaker. But it becomes lethal in icy conditions.
For some reason WB suffers from poor treatment in winter, although it has improved in recent years. The only safeish way to board in the morning when, as is often the case, the treatment is bad (or has been covered by subsequent snow and ice) is to hang onto the grabhandles by the doors and clamber, not step, up into the carriage. If you arrive from London on an icy night the reverse applies, with more risk of falling. This applies when wearing Mountain Boots, which is what I don in such conditions, in normal footware its even more frightening.
All round WB 2+3 is nasty in winter - the new 'shelter' gives none from the sides and there are gradients, some not visible to the casual eye, that it is impossible to stand still on without sliding downhill in icy conditions. Even in damp conditions parts of the platform are treacherous for the unwary. WB also has gradients outside the Platform 1 entrance that leave no safe walking route in and out with ice or snow on the ground.
The irony is that one of those platform gradients (around 45 degrees) drops part of the platform (under the bridge steps) from being at a more manageable level relative to the floor of the usual stock, to a level that leaves a large step up. Its the area that those least able to handle first the gradient and then the platform edge gap will be deposited by the lifts. It would have been relatively simple to raise the platform level, or at least part of it, when the new bridge was put in, which entailed major modifications to the platform anyway - in fact they CREATED the gradients away from the platform edge.