Official figures are rather scant.
If there is an official flight manual (probably in French), then the CAA should have a copy filed when it was first issued a CofA.
If it was imported directly onto permit, then that route won't be available.
It's probably more practical to brew your own. Treat it as a homebuilt and do a few tests to get enough data for planning purposes.
There is a Jodel UK Yahoo group I believe. That may be a good way of contacting other owners to get started.