This practice portal provides links to some very useful practice tools to aid your studies.
Firstly there is the speaking simulator, which will evaluate your speaking and provide correction.
It is not as accurate as a human, but it is worth using to practice.
Secondly there is the Writing checker by Grammarly, and the ‘Write and improve’ by Cambridge.
both are designed to check your written English and also can provide immediate feedback.
Finally, there are some podcasts to help you increase your listening skills as well as tips on other elements of the test.
I will be adding to these periodically. So visit the site regularly and practice.