For me, I think it would make it harder. I've only been a vegan for 1 week, so take this for what it's worth, but we went cold turkey. Originally we had planned to only be vegan at home, and then we realized that might only make us eat out twice as often. lol
However, if you are only planning to use cream for your coffee then why not? I don't think it has to be about being a certain percentage, necessarily. There are no real rules, tailor your diet how it suits you. If you are happy and feel well with a little cream in your coffee then do that. That little bit of cream might actually help you to stick to a plant based diet because it will keep you from feeling like you are living with a restriction that you don't want to live with.
(This might not be agreeable to those who are vegan for animal rights reasons, but I am also and I feel like vegan with a little cream minimizes suffering more than 99% of the people minimize suffering, and it's a good step in the right direction.)
I don't drink coffee, so I don't really have any advice there.