Enable a Customer Group setting

I've been disappointed when building my new site too find that I'm unable to set up customer groups. I currently use these to manage a few customer groups in my shop at the present time. The default customer group is dedicated to current and new customers visiting out online shop and paying as they order. In my soon to be superseded OpenCart site, I have the facility to set up customer groups with different rules for those customers. The two groups that I have set up are for those with credit terms and one with purchase orders. There is no requirement at the checkout to complete a payment (we have our own internal processes to trigger an invoice to be emailed to the designated 'accounts payable' email address for later payment. This is a different arrangement to the EKM Trade Discounts module which applies trade discounts to customers, it would be great to have a feature to include credit terms, as we process all orders via our shop to ensure we prioritise dispatch & workloads.