Hi Murphy, 

Thanks for your question. 
 
On a Zip and Link mattress you will know that they are 2 separate mattresses; The only true way to eliminate this is to add a separate mattress topper to eliminate the feel of the join in the middle. 
 

 
When you disclose you can buy two smaller ones zipped together - Can I please ask what you mean here as we can only construct Zip and Link mattresses in King Size, Super King Size and Extra King Size?
 
We can construct Zip and Link mattresses only in our pocket sprung ranges (Origins and Artisan). The main difference between the 2 ranges is that the Artisan range is constructed with natural fillings and those fillings provide a cool sleep surface. 
 
At your body weight you would be matched with a Medium spring tension to get the right level of support. Please follow the article here for some more information on body weight guidelines. 
 
As a side sleeper you need to avoid anything too firm in the top layers; This is down to the fact that side sleepers can get pressure point pains when sleeping on a mattress that's too firm with no give. 
 
As such I would guide you to our Artisan Tailored Pocket 2000 or our Artisan Naturals. The Tailored Pocket 2000 is constructed with a manufactured dual layered spring system feeling a bit firmer than a true medium in the top layers. Our Artisan Naturals is our true medium feeling model in the top layers giving a slight sink but not too much. 
 
I hope this has answered your questions fully but if you do have any further queries please don't hesitate to contact our office on 0161 437 4419. Our office is open Monday to Friday 8am to 8pm and Saturday and Sunday 10am to 4pm. 
 
Kind Regards, Lee.