Moving a conseratory....

I am looking at a property that has a rear conservatory, that is about 4.3m wide and 3m deep (external dimensions).

If I buy the place, I will knock that down and build a brick extension of about 6m by 5m.

Behind their garage, which is to the side of the house and extends about 6m beyond the rear wall of the house, there is a space... I was thinking I could move the conservatory there, so it is more of a green house, maybe with an entrance on the back of the garage wall.

I am worried I am not being clear, so a quick drawing.....

This is probably obvious, but, I'd need to get planning permission to move my conservatory won't I, when I do the planning for the extension? Idea is to convert the garage to a room with access to conservatory.

Yes, you would need planning permission for both if you plan to do both parts at the same time, or you are doing the rear extension part first.

If you were to build the new conservatory first of all, you might be able to do this under the 'permitted development' regulations without having to apply for planning permission, as long as you conform to the restrictions on extending outbuildings (have a look at the Outbuildings section on the Planning Portal).

I think my plan will be:
carefully dismantle.
try to use as a mini conservatory or summer house
or sell