Add a message to the cart page reminding somebody to add X amount to their basket to benefit from a discount

Site URL: http://www.skinnypiginteriors.co.uk

I am trying to incentivise people to buy more from the site and have set up discount codes at £50 and £75+. I would like to remind people at the cart stage that if they add X amount more to their cart they will benefit from this discount. Is there a way I can do this? Thank you