Used these sites, they were a massive help
Free Tests
https://ieltsonlinetests.com/
Paid Tutorials - Self Paced
https://ieltsonline.com.au/courses
If you practice a lot of the reading and listening tests, you should have a good idea of what band you belong in and where your weaknesses are.
For Speaking and Writing - we used the paid tutorial site, and found their lessons quite helpful.
Even if you are a native English speaker, I would suggest a lot of practice - we spent close to 40 - 60 hours practicing before we attempted the test. During the Writing test you really need to pay attention to the time as it goes quick, and for the speaking - you need to be able to use formal language, and speak continuously on random topics for at least 3 minutes without repeating...so practice with a friend.
Good Luck