I'd have assumed the same, if the store is vented.
If installing a stove legally, you need to be either going down the notify building control route or registered as a competent person for solid fuel with HETAS, OFTEC, or similar organisation. I've seen illegal installs that work and are reasonably safe, but your original post did make my hair stand on end slightly because you don't seem to understand the basic principles of a gravity system.
Broadly speaking you need to consider expansion, boiling (water expands 1600x when it boils), and where to dump the heat. The system has to be idiot proof and has to be safe to use even if the fire is fully loaded, you fall asleep, and the electricity supply or pump fails. This means gravity circulation is a must. You need an open vent, which means you really do need a header tank. Some clever computer controlled solid fuel sources dump cold water through the boiler if the system overheats (via a mechanical valve) and this probably wrecks the boiler but it does mean you can seal the system instead of using a header tank, but what you have is a basic backboiler and this wouldn't be appropriate. This doesn't mean you HAVE to have a hot water cylinder, but it does mean you HAVE to have gravity circulation. Also, find out what the heat output from that boiler is - it may or may not be huge.
If you really want to go down the DIY route, I suggest you get information from the solid fuel association and do a bit of your own research then come back to us. At the moment (as of your original post) you are barking very much up the wrong tree.
Not sure why your stove has 4 ports. I have seen 4 port backboilers that seem to be designed for semi-gravity systems where 2 ports are pumped and the other two are feed and vent connexions and these will work if one high and one low are blanked, but I see no advantage in blanking off and wouldn't do it unless I was sure that that boiler was designed to be used in that way.