If it's not Seat doing your first service.Make sure the garage doing it are VAT registered.Also,make sure they use genuine Seat parts,and you get a copy of all the work done,along with a break down of the parts used.Make sure you don't go 30 days or 1,000 miles over your service interval.
If you don't do all of the above,your warranty won't be worth the paper it's printed on.