I suspect javascript is the best way to do this but I'm not sure. I want to create a simple form field where part of a url is a variable that the user enters and then when they click, it clicks through to the url based upon what they input. The url would not be submitting to a script or anything just to a URL. In some cases off site. So for example:

Number of rooms in your house:
| Enter Text Here | Submit

When submitting all of the URL except the variable would be predefined and the page would click through when they hit Submit e.g:


Any insights appreciated.