The kit on Haldex repairs looks spot on and includes the right fill/drain plugs that will fit your car. They haven't changed design of them for years. It doesn't include the pump bolts but that's not the end of the world.There is a single Haldex Pump on your Cupra Ateca, located at the front of the car up by the gearbox.
Looks like Haldexrepairs.co.uk offer a comprehensive kit, although query the Fill & Drain bolts for the Cupra Ateca.
Useful Blog post from Awesomegti.com;- Haldex Servicing - Why and when?
When I enquired with my Main Dealer last year, I was advised the Service Interval on the Haldex Pump is every three years (30K miles?). Cost £149.
Hope this helps.
I thought the pump was at the rear of the car, is the pump easily accessible?