TT, I never said there should only be a focus on the cream of the workforce. For most of this thread I've been posting about the bottom of the global workforce - smallholders, women who deal with sewage, the poor. I'm not sure getting more women into positions of power in most companies helps those women because many companies are predatory and woman at the top of those companies would probably have to work against the interests of most women. But I do think more women in charities, law, medicine and politics helps poorer women.
I think feminism has a range of different main areas of interest which I would say are - reproductive rights, violence against women, poverty, environment, employment roles, social representation and political representation. If you are particularly interested in employment roles, you may well see a lot of stuff about FTSE 100, and that will be your perception of feminism. I mainly get involved with stuff about reproductive rights (maternity care for all women), poverty (so unpaid and poorly paid women) and environmental issues like damage to women's land, dumping of unsafe waste that women then have to process etc. So I don't notice the FTSE stuff because it's not an area I'm interested in or know a lot about.
If you've identified a gap in women's access to certain employment roles, there may be too few feminists involved in resolving that, and I'm sure they'd value your help and the help of any feminists (male or female) who work in those fields. But feminists are stretched pretty thin across a whole range of human rights issues for women (and often individually contribute to other social movements too). I'm not convinced that if lot of us become builders and bin men, more men collectively will see women as equal and resolve those other women's rights issues.
So in short, go for it. Lots of girls currently at school will benefit. There's no reason for us all to focus on the same stuff.