The primary route for Polish refugees was via Romania or Hungary. Those two countries remained neutral in 1939, walking something of a tightrope in balancing support for Poland with pressure from Germany and the Soviet Union. As such Polish combatants who escaped were interned, but not particularly strictly, tacit support allowing large numbers to make their way to France via routes including Yugoslavia, Italy, Greece, and ships to Beirut in French-controlled Syria, until increasing German pressure curtailed the flow in early 1940.

Estimates I've seen are for 30-40,000 escaping to France (Anita Prazmowska puts the figure at 34,000 in Britain and Poland, 1939-1943, Stephen Zaloga has 35,000 in The Polish Army 1939-45, Jerzy B. Cynk has 38,000 in The Polish Air Force at War). A further 45-50,000 recruits were found in France, mostly pre-war Polish émigrés, for total military personnel of 80-90,000. After the fall of France some 20,000 escaped to Britain to join the few thousand Air Force personnel already training with the RAF.