What this mean to you?
Type 1 and 2 is most sun sensitive and will have a hard time developing tan, reason for this is that skin will burn without the chance of pigmentation. Your skin gets tan from a pigment called melanin. Special cells in our skin produce melanin. When skin cells become damaged or unhealthy, it highly affects melanin production in negative way. To avoid burning you would use sun screen, but this will also prevent tan.
Melanotan is god sent gift here, it will significantly speed up pigmentation process thus preventing skin burning, but this does not mean if you have taken melanotan you are automatically protected from burning, that being said if you are very pale take extra caution.
Generally less number you are in Fitzpatrick scale, more time and melanotan it will take to achieve deep tan, but once you have it maintaining your new skin color is easy regardless of skin type.