Sex help (caution) :)?

Hi I'm kinda afraid of letting my boyfriend give me head, I give him b.js a good few times a month 'cause I don't mind it, but he has never given me head. He tried to but I stopped him before he went past the underwear 'cause I don't know what he'll think. I'm completely clean, but I just feel like what if he doesn't like it? Thanks for any advice