The fuel shortages could cause problems in many industries. I have read that Btistish Army's trained personnels are ready to drive fuel to service stations. Also, the UK government are offering temporary visas for foreing drivers.
I wonder whether they did consider the shortage of workers, which has threatened supply chain, while planning the Brexit.
They did consider the shortage and expected locals to backfill. Didn't happen in most instances as the shortages are often in positions that locals don't want to work in, which is why they were filled by foreign labor originally anyway.