Hi Lesley Anne,
Congrats on the new client.
Your best course of action would be to check out the ICB resources via the below link:
Here you will find all you need to ensure you remain compliant including a standard Letter of Engagamenet template and a guidance on how to use the template.
You will need to ensure you have LOE 's in place for each of your clients under ICB requirements as it acts as protection for yourself as well as your client in the event of any disagreements about fees etc.