Grammar resources available via this guide
You can take a Grammar Diagnostic Test which helps you to identify if there are any gaps in your grammatical knowledge. The online version is below. Make sure you download the feedback sheet (below) after you have taken the test to find out where to get help with the areas where you might have made mistakes
A list of some external sites for learning and practising grammar.
The Internet Grammar of English (University College London)
Grammar and Writing Activities ( Bristol University)