Historical note: Neither the S.A.S. (constituted on May 31, 1950) nor the F.F.L. commandos unit (created on July 1, 1948) actually existed on D-Day!
The SAS certainly DID exist on D-Day, although not in its current form as it was disbanded at the end of the war and subsequently re-formed.
From Wiki (based closely on the SAS's own website...)
The Special Air Service was a unit of the British Army during the Second World War, formed in July 1941 by David Stirling and originally called "L" Detachment, Special Air Service Brigade â€” the "L" designation and Air Service name being a tie-in to a British disinformation campaign, trying to deceive the Axis into thinking there was a paratrooper regiment with numerous units operating in the area (the real SAS would 'prove' to the Axis that the fake one existed). It was conceived as a commando force to operate behind enemy lines in the North African Campaign and initially consisted of five officers and 60 other ranks. Its first mission, in November 1941, was a parachute drop in support of the Operation Crusader offensive. Due to German resistance and adverse weather conditions, the mission was a disaster: 22 men, a third of the unit, were killed or captured. Its second mission was a success: transported by the Long Range Desert Group, it attacked three airfields in Libya, destroying 60 aircraft without loss. In September 1942 it was renamed 1st SAS, consisting at that time of four British squadrons, one Free French, one Greek, and the Folboat Section.
SAS patrol in North Africa
In January 1943, Stirling was captured in Tunisia and Paddy Mayne replaced him as commander. In April 1943, the 1st SAS was reorganised into the Special Raiding Squadron under Mayne's command and the Special Boat Squadron was placed under the command of George Jellicoe. The Special Raiding Squadron fought in Sicily and Italy along with the 2nd SAS, which had been formed in North Africa in 1943 in part by the renaming of the Small Scale Raiding Force. The Special Boat Squadron fought in the Aegean Islands and Dodecanese until the end of the war. In 1944 the SAS Brigade was formed from the British 1st and 2nd SAS, the French 3rd and 4th SAS and the Belgian 5th SAS. It was tasked with parachute operations behind the German lines in France and carried out operations supporting the Allied advance through Belgium, the Netherlands (Operation Pegasus), and eventually into Germany (Operation Archway).
At the end of the war the British Government saw no further need for the force and disbanded it on 8 October 1945. The following year it was decided there was a need for a long-term deep-penetration commando unit, and a new SAS regiment was to be raised as part of the Territorial Army. Ultimately, the Artists Rifles, raised in 1860 and headquartered at Dukes Road, Euston, took on the SAS mantle as 21st SAS Regiment (V) on 1 January 1947.
In 1950, a 21 SAS squadron was raised to fight in the Korean War. After three months of training in England, it was informed that the squadron would no longer be required in Korea and so it instead volunteered to fight in the Malayan Emergency. Upon arrival in Malaya, it came under the command of Mike Calvert who was forming a new unit called the Malayan Scouts (SAS). Calvert had already formed one squadron from 100 volunteers in the Far East, which became A Squadron â€” the 21 SAS squadron then became B Squadron; and after a recruitment visit to Rhodesia by Calvert, C Squadron was formed from 1,000 Rhodesian volunteers. The Rhodesians returned home after three years service and were replaced by a New Zealand squadron. By this time, the need for a regular army SAS regiment had been recognised; 22 SAS Regiment was formally added to the army list in 1952 and has been based at Hereford since 1960. In 1959 the third regiment, 23 SAS Regiment, was formed by renaming the Reserve Reconnaissance Unit, which had succeeded MI9 and whose members were experts in escape and evasion.
Also, I think "Commandos FFL" refers to "Commandos Forces FranĂ§aises Libres" - Free French Forces in this context.
If you are thinking of the "French Foreign Legion Commandos" that would be "Commandos LE" (Commandos LĂ©gion Ă©trangĂ¨re) in the French language