YABU, like BikeRunSki, I am a professional engineer (not civil) - I am almost 60 so there were a lot less female engineers around when I went to uni and started my career than there is now.
In most teams I have either been the only female, or one of 2. There are more around now, including one of our top global managers, but still very male dominated. I generally am the only female in many meetings even now.
I have always been treated professionally and found male colleagues totally accepting of me. My role also includes site visits, so often travelling to other parts of the country, staying in hotels. I am less likely to go drinking after a meal when working away, but that is more my age than anything! I have never felt left out of conversations when travelling or eating with them.
I also found work, with its different atmosphere/conversations, a refreshing change from home life when the kids were younger and I was mixing a lot with other mums on my days off.
I did have a social life with some male colleagues when in my 20s, but not in recent years when married with kids. I am friends with a few female colleagues but even that is limited as we are scattered around a large area, plus have various family commitments.
A male dominated environment does have advantages too, I have never encountered any bitchiness, everyone is generally straight talking. We don't go in for collections for every celebration, I sometimes read a MN thread where they collect for anything and everything and am aghast!
So I would say, just go in with an open mind and remember you are there on merit.