mm, not sure. By rights you can only bring in a value of up to £18 without being liable to be charged. Then it's hit and miss as to whether they get you. You should look on HM Customs and Excise website.
I was on my way to work this morning and was just thinking how I haven't seen a single Z since I got mine! Then low and behold coming towards me (near A19 roundabout) another lovely sunset. I waved and got a nod and a smile back.