Hi Bjay there are a couple or 3 ways to increase the text size left ctrl key and the + key pressed at the same time. In Firefox there is the zoom options in the view menu, you can select to zoom in or out and select zoom text only. Every web browser will have a view menu. Some browsers will have menu's turned off by default thou.
A third option is stylish an extension for firefox which can tweak many websites including this one.
It looks like an upgrade to the cms (content management system) has broken a few things. The CMS is a complicated beast at the best of times and the developers will be working on fixing the problems. Unfortunately the publishers (one of many users of the CMS) will be waiting for the fixes to be released there will be many sites all over the world with the same issues.
So the problem area's will need to be identified, code written and tested released to the world, then the publishers of Gardeners World will want to load the new version on to a test server test it themselves and finally upgrade from this version to the new one.
Unfortunately downgrading to the previous version is not really an option there will be changes between the databases used and other parts of the system. So the only option would be to start fresh or restore from a backup losing everything that has been added since the current revision was installed. It's likely there are security issues with the previous version too which will be part of the reason for the upgrade in the first place.
In the end all we can do is sit tight and wait, hopefully the work around will help with the text and we will have to make do with how things are working now. Better to have the site now as is than lose it for a month or however long it takes for a new version to be written , tested, released and hopefully tested again.