Sun Porch

We have a veranda outside our kitchen. It isn't insulated under the floor. It is open underneath. Also, we want to put a hose to blast the heat of the main house there. As there is no source of heat there. Is it really needs to be isolated and under his regime? And it will be warmer in the winter there.

unless you have money to burn ... I would like to isolate ...

Assuming you are in England it seems that you have opened the door between the conservatory and the rest of the house. So now, the porch becomes an extension and must be put to the insulation standards as the rest of the house. You can simply ignore it, but it will turn against you when / if you want to sell.

Yes you do, otherwise you will lose heat in winter.