Should I take it?

A thesaurus is good for identifying synonyms—native speakers often use them to identify just the right word when writing. If you are doing a lot of writing or trying to expand your vocabulary, it might be useful. Just make sure to look up the words you find in a dictionary to understand exactly how they’re used.

sure

Collins makes good dictionaries, so I think their thesaurus should be good too. And yes, you look up a word in it and it will show you its synonyms and antonyms. I don't know how useful it will be right now, but if you end up doing a lot of writing, especially academic writing, it will help.

A Thesaurus is nice, it can help you expand your vocabulary, so if it's not expensive, go for it. If you can find it though, I really recommend trying the Longman Language Activator. It's a great resource which doesn't just give synonyms, but synonymous phrases grouped by different functions.

There are loads of free online thesauruses TBH so I'm not sure it's worth spending cash on. The Collins Dictionary is probably going to be more use if you want one physical reference text.