Use Mometum 99 or Shell VPower 99. I believe on the flap it should say 98/(95) RON, so 95 RON for emergencies only. Unless you are in countries where 95 is the highest you can get. Not sure how long your Cupra lease will be...but I'm guessing they will come with Conti 5P tyres, they will go quickly and are not the best (from consensus of everyone).. so keep an eye out for good deals for Michelin Pilot Sport 4S tyres, might suggest if a good deal comes up, just buy the tyres in 235/35 R19 size, and store till you need them. You are likely to need to change tyres prior to the end of your lease.. I would say drive it 'normally' but not foot flat / till redline for the first few hundred miles...as always, wait for engine to be up to temp before giving it some.
Is using 99 noticeable ?
We use it currently as Tesco are our closest petrol station but I can’t tell the difference. Wife says it gives more mpg