I'm an italian Red Cross volonteer and here our ambulances has volonteer rescuers and a professional nurse (so 3-4 people in each rescue team, of course one is the driver). A few ambulances has a doctor in their team: these ambulances are involved only where a people has a very critic conditions.
What's the organization in UK? All teams have a doctor? Are volonteer rescuers involved?
Of course here in Italy ambulances are managed by public service too. Each region has a control room connected with public number "118" (free).
Unfortunatly we haven't yet a universal number (like 112) for asking rescue: at the moment "112" in connected with "Carabinieri" control room, "113" with Police control room, "115" with Fire Department control room and "118" with Emercency First Aid control room.