you'll be fine xx
Just be yourself with the children, do what you normally do and enjoy being with them. Let them take the lead and help communication by being available, interested and knowledgeable.
If necessary you can suggest things - answer queries with 'let's go and find out' and reply to requests with yes .. wherever possible
If it helps maybe check with your leader/manager if you can take in /choose a different or new story book to read - one from home if you have any would be great - for reading in the quiet area or to a larger number of children/story time and also maybe ask your assessor how they'd like to be introduced to the children.
I hope this helps
All the best for it xx