Yes - entering your UK registration normally returns the correct tyre size and suitable options, but always confirm the details match the tyre sidewall, especially if wheels have been changed.
Check the tyre sidewall for a format like 205/60 R15, or look in the driver door jamb and the owner’s handbook for the manufacturer-recommended sizes and pressures.
In most cases, yes - choose a load index and speed rating that meet or exceed the vehicle specification; selecting an incorrect rating can affect safety, insurance and MOT compliance.
After choosing tyres, you select a nearby fitting partner and appointment slot during checkout; your tyres are delivered to that garage and fitted at the booked time.
The legal minimum is 1.6mm across the central three-quarters of the tread around the full circumference; replacing tyres before this point can improve wet grip and braking.