Have your Terms page open in a popup window during the checkout process. This will keep users in the checkout funnel and wonâ€™t let them get distracted by a new page opening.
Once a customer has added products to their cart you want to remove as much clutter as possible so users donâ€™t get confused, wander off, and leave a cart full of items just sitting there begging to be purchased. One of the things you donâ€™t want your customers doing is clickingÂ outÂ of the sales funnel onto your Terms & Conditions page and wandering off. Open that page in a popup to keep things as simple as possible.
The popup looks great by default and can be styled however you want with CSS to match your theme.