Ear piercing & stretching help!?! (UK)?

A "stretcher" is a taper. You can get a taper kit at tribalectic.com and possibly a tattoo parlor. I think online would be your best option though, as a tattoo parlor would be ordering them offline & probably overcharging for them. Keep in mind though that tapers aren't jewelry, so you will still need to buy a pair of jewelry for each size you're at.