One parent, only at home - more harm than benefit?

Hello,

I am the mother of a three month old baby boy, my husband and I are both Turkish, but as I lived overseas since early childhood my mother tongue is English. I would love to be able to give my knowledge of English (and the accompanying love of diversity and multiculturalism) as a gift to my son, and we had been planning to raise him bilingual.

However I didn't know much about techniques, and reading up I only recently learnt that we had to choose from OPOL or minority language at home for him to really learn the language.

My husband knows English as well but not as well as I do, so the latter is not an option. I am willing to speak English with my son, however I am afraid that I won't be able to do it consistently in public, or that he may not be willing to speak English with me in a majority Turkish environment even if he understands in the future. However I don't want to give up on this chance, and thought of asking advice here.

If I speak only English with him at home, and his father Turkish (perhaps some English too sometimes, at home?) but speak Turkish to him when I have to in public, with family etc. will this mess up his language acquisition for both the languages? Considering the fairly conservative environment we have here, I'm afraid this is inevitable. Do we have no option but to just stick to one language, Turkish, if we have to do it this way? I don't mind the expected delay in learning the languages, but don't want this to affect his learning of Turkish negatively, or confuse him too much. What would you suggest? 

Also I am just curious (and have yet to read everything on the site!), although I don't think it is an option for us, if we used the minority language at home approach with my husband, how exactly would he learn Turkish? I mean, would his knowledge of the language be limited to what he learns when he starts preschool, which is a long way off for now. Aren't we supposed to start at all beforehand?

Thanks in advance!