What you are probably looking for, first of all, is a content management system (CMS). This is a package of code that you upload to your server and around which you build your site. A CMS provides the kind of functionality that you are after—without which your learning curve would be far too high (at least in that timeframe) as you’d have to learn all sorts of complex programming.
The basics of web design are HTML and CSS—which are relatively easy to learn—so start with them first. Then look at CMSs, into which you can incorporate your HTML and CSS. I recommend ExpressionEngine, which costs a bit, or free alternatives like MODx or WordPress.
Then, if you want to spice up the front end of your site a bit, look into JavaScript. An easier way to approach JavaScript is to learn how to use a framework like jQuery, which does a lot of the heavy lifting for you and saves you from having to learn the most complex programming bits of JavaScript.
I was wondering what sort of tech I should build the site on? I see all these terms branded around, HTML5, JQuery, CSS3, Zend, Ajax etc etc. … I would want to take advantage of some of the latest web technologies (to make development easier), but at the same time not create something which only runs on the very latest browser updates, what would be a good balance?
You can tinker with HTML5 if you must, but really, it’s still in the womb and not ready for serious production. Little bits of CSS3 are ready for use in the most modern browsers, and are safe to use, as long as you aren’t attached to identical cross-browser rendering. jQuery offers some Ajax functionality, but don’t go overboard with this stuff. Remember that content is king, so only use fancy stuff to enhance that content where really needed.
Really, the web is a thin layer of cake (HTML and CSS) covered in a lot of icing (JavaScript, Ajax etc). A cake with no icing is fine, but a pile of icing with no cake is … well … a bit sickly and not much use, so make sure to keep a perspective on the basics. 