Being iPhone ringtones, you first download them to your PC/mac, import them in to iTunes and then sync them with your iPhone.
Instead of paying 99c per ringtone, this iPhone ringtone service costs just $1.99 per month and gives you unlimited access to over 250,000 ringtones. Yes, technically you can download all 250,000 ringtones.
The iPhone Ringtones are avaliable in loads of countries, including the UK.
Check out iPhone Ringtones