An online source from the Canary Islands claims that the cultivar "Gomera," specifically "Gomera-1" is the most cold hardy rootstock/mango variety available in Europe, growing in coastal Mediterranean areas. Apparently the mature trees can survive short freezes up to -4°C, and its even been indicated to fruit in Southern France (although I assume it has a million protections going for it).
If not that, the Mallika dwarf mango is one available in the US that is suggested for attempting to plant in zone 9 or colder regions. No clue on availability for that cultivar in europe. Good luck.