See what happens at Deauville LFRD during a day (all times local):
From sunrise-30min: daylight VFR permitted (anywhere in France). No ATC on duty (airfield frequency unmanned): it does not matter. Deauville TMA and CTR are downgraded to class 'G' : no Xponder compulsory, pilot own responsability to fly with ground viz of minimum 1500m and no cloud below 500ft agl. The pilot transmits blind on TWR frequency (ie 118.300) in French or in Frenglish (use of radio compulsory at LFRD anytime).
At 0800 (Sun, BH: 0900) till 2000 anyday: TWR ATC in duty, CTR class 'D', ie Xponder mode C compulsory, minimum viz 5000m, at ATC convenience minimum 2500m (see LFRD VAC chart).
At 0800 (Sat, Sun and BH: 0900) till 1930 anyday: the Terminal is open.
At the same time (0800/0900-1930) Customs are available (here at Deauville without PPR or PNR): Pilots may arrive or depart to a non-Schengen country.
At the same time (0800/0900-1930) fire tender is operative.
At 0830 (Sat, Sun and BH: 0930) fuel is available till 1200. Again available at 1400 till 1900. Fuel delivery is not possible at LFRD during the dreadful French lunch time, anyday (unless PPR).
At 1930 the terminal is closed.
At 2000 TWR is unmanned.
At SS+30, day VFR flying is not possible at Deauville or elsewhere in France.
The most important point to notice is the terminal time opening. Since 911, airfields and airports with commercial traffic are surrounded (anywhere in France) by a seven-foot fence. This is not clearly said in VAC charts. When French terminal are closed, it is quite impossible to go airside <-> publicside (both ways). It is like the Berlin wall !
Let's suppose an aircraft arriving at Deauville in Summer at 2030, transmitting blind at this time. Terminal closed. The local flying club little gate (normally closed) opened with a card is strictly only for local member pilots and their passengers. By no way other people may get through. So the pilot has 2 possibilities: either to sleep overnight in aircraft, or to start up and depart quickly for a near-by airfield (with no fence): Bernay LFPD or Falaise LFAS and land prior SS+30. Let's say that, as Terminal and ATC are closed, no movement is noticed (even if the frequency tape still records all speech H24) : no fee has to be paid !
Hope that helps.