How to set LibreOffice to suggest corrections for UK English?

It's pretty straightforward to setup British spell checking- I did it a while ago as I am in the UK, so it's pretty important for me. My version of Libreoffice is exactly the same as yours: the default 3.5.x series version for 12.04.

For some reason this UK dictionary isn't included with the Ubuntu packaged version, even though it is when you download it on Windows and the UK spell checking is enabled.

Please go to the official list of dictionaries and choose kpp-british-english-dictionary and download it to your desktop or downloads folder. Now open that downloaded file with LibreOffice itself and you will be presented with this screen:

Now, make sure that it is enabled, and restart Libreoffice and open Writer, select English UK and it will auto highlight your mistakes as below, as long as the other settings are set to English UK in Tools > Options > Language Settings > Languages.

Also, it is important to make sure AutoSpellCheck is enabled.

On getting also thesaurus/synonyms, there is already this answer.

I had this problem with a fresh installation of Lubuntu. I set everything that I could to English (UK), but spell checking did not work. I eventually found this:

Cannot set language for spell check

I fixed the problem by opening a terminal and typing:

sudo apt-get install hunspell-en-gb

and entering my password when prompted.

The red squiggly underlines finally appeared in my document.

As it has already been said, the previous solution does not work because of a dead link.