.... but are the ferries and planes going to run low on fuel too?
In a word, no. Simply because the ferries will tank up in the UK or Ireland and the aircraft wherever they are travelling to/from (and, as a visitor to LM form abroad you're not interested in internal flights). Some LoCo airlines fly on 'just enough' relying on tanking at each destination, however the model is easily changed for flights into/out of France as the capacity of A319/320 & B737 is more than enough to allow them to do a return journey.