Part of the degree that I am studying in the UK involved Geography and so in those lectures there were quite a few males in my classes for a mostly female dominated University. I didn't choose the University because it consisted of mostly females, I didnt know that statistic until I started the course. I chose my course because I loved the subject, I chose the University because I loved the city, how small it was and the history to it. If you love the subject, your good at it and passionate about it then what does it matter about the amount of males on the course? Have you tried welding before, done a trial day to see if it is for you?
Personally I like male and female company however if you feel you need more female company than what your class consists of then remember that you can make friends outside of your classes too. Anyway don't let old fashioned values get in the way of what you want to do or who you want to be, if you can't physically do something then you will probably need to think twice before doing it but if it is just people telling you that you can't do something you want to do because you would be within a minority within a class then just tell them this is what I want to do so this is what I am going to do, deal with it.
Also here there are possibilities to change courses early on if you find its not right for you if you are unsure maybe you could ask if your college lets you change courses in the first few weeks or so. Make sure you get online and go research all your options, what careers could the degree get you, would you want to do that career, what salary would you get, how many jobs are avaliable, are their any health risks to the career? Read around the topic then when you are aware of what the degree would mean for you make an informed decision as to if you want to do it. What you want matters in your career choice, not what people want you to want.