It’s official: Amazon Prime Day is back next month, and we’re expecting to see discounts from top brands like Dyson, Shark and Garmin. The retail giant’s biannual sale is available for Amazon Prime members only, so the first thing to do if you want to take part is to consider signing up for a 30-day free trial. Make sure you time it correctly, though – we’ll update this story as soon as we know the exact date the sale is going live. To sign up for a free trial, go to Amazon Prime and follow the instructions to set up your account. After the trial has ended, you’ll then be charged £8.99 a month to continue the subscription, so remember to cancel it if you no longer want Amazon Prime. Below, we've rounded up everything you need to know about the next Amazon Prime Day sale, plus some of the best deals on expert-approved products that you can snap up in the meantime. Read more: Asda’s charming garden furniture starts at less than £20 – here’s what to shop Amazon Prime Day is a sale event for Prime members.…