QuickBooks offers a standard 30-day free trial period, allowing you to explore all it's features at no cost, Calum.
After the free trial ends, the promotional offer you signed up for will begin, and you'll be charged £1 per month for the next six months. The message you're seeing refers to the conclusion of your 30-day free trial, after which your discounted subscription will start automatically.
Please see screenshot for reference:

You can also contact our Live Support team to discuss this further about your subscription plan.
Here's how to connect with them:
- Log in to your QuickBooks account.
- Select the Help (?) icon.
- Scroll down to select the Contact Us button and follow the prompts.
- You will be able to request a callback or start a live chat with an expert.
Please check their support hours to find a convenient time to reach out to them.
You can always come back on this thread if you have any other questions related to QuickBooks.