Yes, I've always joined the union and attended meetings, wherever I've worked. One workplace wasn't unionised when I first started there in the 70s, then a union was invited in for those members who wanted to join. One of my colleagues said he wouldn't speak ever again to anyone who did, and he kept that up (silly man) for about a week. I think he was surprised by how many people he had to be careful not to speak to during that time! 
To be honest, UNISON weren't a lot of direct help to me when I needed them, but the very threat of "Well, I'd better run this past my union rep" gave my management pause for thought and me the chance to sort out my own problem. I did hear that shortly after I'd left they started to take a lot more interest in what was going on in that particular workplace, so others did get the help they needed.