These are made by Larini, and despite the photo, are single exit.
Alternatively, they could supply you a used manifold off a UK 1994 1.8 and a used 440mm cat (about £130 plus vat). That way, you can fit the exhaust you’ve got to your car. Someone else can advise if fitting this shorter cat will compromise emissions for the MOT.
The UK 1.8 manifold will have the EGR fitting you need; an import manifold will be missing this. The aftermarket stainless steel headers sold by MX5parts and others all generally have the EGR fitting.