The cost of owning a dot.com or dot.co.uk is very low compared to when the original dot.com boom happened at the turn of the century (that's 2000!). You can enrol on costly evening courses, but the chances are that you have access to professional web design tools like dreamweaver at school or college.
There are other software packages you can download for free, links to a few here, and free web hosting services that allow you to build instantly. If you want your own dot.co.uk for free and hosted by google, then for a limited time only you should click here
To learn the basics, then you can visit the free web school where it all began: