Given that description it just needs to be driven - not "pootled" with.

An Italian tune-up might work wonders.

Better petrol seems to be informed opinion. Have a look at this

www.seatcupra.net/forums/showthread.php?t=189738

I'd take it for a run, wait until its fully warmed up to normal operating temperature and then give it some beans to blow out any cobwebs. V-Power over several tank fills might help with its detergents to clean up deposits if any have built up but thats more of a benefit to much older higher mileage cars and is unlikely to be the cause of poor starting.

If that doesn't improve things I'd drop it in at the dealers as it will still be under warranty and get them to check it over.

A good run of 20+ miles would help, and try overriding the autobox to get the revs up too for a couple of mles.

Might be worth checking the battery terminals are nice & tight, too.

Millers Petrol Eco Max seems to be very well recieved and I've had good results on my van with the diesel version so I'm buying some for my petrol car. There is a one shot version for cars that haven't been treated before. The normal stuff should be used regularly.

I get much better fuel economy using Jet fuel compared to Tesco in both the van and car. The car (Saab 9-3 Aero with Maptun st1) also runs and "goes" noticeably better on Jet super98 compare to Tesco momentum99. so I would advocate a "branded" fuel

Is the starter motor sluggish and slow to turn the engine, or does it spin vigorously and the engine just not fire as quickly as before?