CMS Website Required For Customers To Print/SMS Coupons

I have started a new Coupon Business in my town and require a CMS website for customers to either print the coupons or to SMS the coupon to their phone so that they can present it in the shop. The website will have similar features to the groupon uk website and as it is pretty much the same concept except that it is only local to my town and there is a printed coupon book. Website special features include: Being able to print a coupon, being able to SMS a coupon to your mobile phone, UK only. Countdown timer for special offer. Display the number of coupons printed/sms per offer. User registration. All pictures and text will be provided. I only need the website set up, i will input all the content. I have used DNN before but I am open to any CMS system and have a good knowledge of computing/websites and html.