I have, as SLF back in late 1980s at LGW, taken off in a 737 classic with similar amounts of snow accumulation. It blew off, we took off, and were soon up in the sunshine none the worse for wear.
Unfortunately the MD83 ahead of us was not so lucky. The snow from its wings went straight into the engines, which were unimpressed. The aircraft did get airborne, just, and then scared its pax witless burning off fuel before landing, at the second attempt, on Filton's long runway. It was a close call.