I agree with this poster. I was also raised as a Muslim, in a Northern UK city where lots of Muslims live. I wasn't religious at all in my 20s but found myself becoming more and more spiritual post 30. I don't wear a hijab, but dress as modestly as I can and I think for me it's a developing journey. I find a lot of solace and peace in religion.
I have a mixed marriage myself. My husband is white British but converted to Islam (he was a muslim before we met) and he prays, fasts etc. We follow the middle path version of Islam and try to be the best Muslims we can be in terms of our actions and deeds etc. Maybe looking at us outwardly, you would not guess we are Muslim, but religion is a personal thing for me and I'm focusing on my own journey back to Islam.
In terms of marriages, I have seen many mixed marriages and the majority work better when people are honest with their family. If their partners are not religious, it's better to be honest and say it. That way the expectation is not there. Expectation is your enemy. They won't be happy, but at least the truth is out there.
The problem you have OP, is as life goes on, many people do become more religious or spiritual, so his religious views now might not be the same in 20 years. Also, children do not lie, so you could be exposed that way. What a horrible thing to live with. Not to mention, children have to be taught islamic prayers, phrases (InshaAllah, mashaAllah) and learn Arabic to read the quran, and be taught to clean themselves (wudhu) in preparation for prayers etc. There are lots of rituals and they all come part and parcel of growing up as Muslims. What will you do, if you take them to see family and they don't have this knowledge.
99% of the Muslim men I know, who married women who were not born muslim, are expectant that the children grow up in the faith.
Honestly, I would think long and hard about this. Try to persuade him to be honest otherwise the burden is yours to bear. And he might change in the future, could you live with that? I do find from the people i know, many newly religious muslim men push their faith onto their wives (if they weren't born into the religion) which is wrong! Recently during the school run, a friend has started wearing a hijab and said she was under increasing pressure from her husband (who was not religious when they married but became so after their daughter was born) and she's told me she feels like she's losing her own identity. Don't let this be you.
Hiding things from your parents is common in the Asian culture. I've done it myself. But there comes a time you really need to separate yourself and step up and say this is me, accept me or disown me.