Welcome, Sam, to the OEM forum.
Is that the grid meter or the generation meter that I can see?
I think you’re going to struggle to get the standard 100 A c.t. in there - even just one. Adjacent current-carrying cables do have an effect, it’s not major. A touching (but outside the core) cable carrying 100 A gave an indication of 160 mA in the c.t. So something to be aware of but not a major worry, I’d have thought. Strictly speaking, there should be a barrier between the cables at 240 V and the c.t. cables, but that’s hardly practical in there.
If you do need to get two c.t’s in there, you might be able to use a ring-core (rather than split-core) of a lower rating, that will therefore be physically smaller, on the PV infeed. And there’d be no harm in stripping that T&E back further (you need a bit more earth sleeving) to give you more of the brown core to play with.
You could look at the YHDC SCT006. This used to be stocked in the shop, that would be OK on the PV infeed. But it has disappeared, though no doubt it’s available elsewhere.
If you use (almost) anything other than our standard 100 A c.t, the emonPi will need special calibration on that channel, and that brings its own problems.
But you can’t do the same with the grid connection. Presumably, you can’t get at the tails between the supply fuse and the meter? Would I be right in thinking there’s a meter box on the other side of that wall? That would be an alternative place for the Grid c.t. If you can’t do that, you might manage to make some space at the left-hand end, by moving cables around.
And you do have a “Type 2” system (because you can’t measure the total house consumption on its own, without the PV contribution).