Ok , I've downloaded the final 3.3 and read the installation instructions this time...
/If you choose a custom installation, you will see a dialog box that lets you choose what LibreOffice components to install. Open the dropdown boxes and make your choices./
/At this point, you can choose the language packs you want to be installed. English and the language of your operating system are selected by default. Also, all dictionaries are selected by default. You may want to select only those which you actually need. You can also deselect unwanted extensions. Make your selections, and press "Next"/.
Although I'm using Windows 7 with the Welsh language pack as noted above, the Welsh language pack was not ' selected by default' I had to manually set the language pack through the Custom Installation setting. It then worked.
There are some issues with the translation not being complete. The translation for 3.3 in OOo Pootle was complete but the version in Pavel's repository was not. OOo 3.3 will not appear in Welsh but I'm hoping that it will be picked up for 3.4.
Thanks
Rhos