I strongly suggest you check out AHKAH's designs, it's a Japanese jewelry brand which owns a couple stores in the UK, their delicate designs are quite famous, and very high quality, I bet you can find one thing or two that you really like~
here's their Liberty website:
http://www.liberty.co.uk/fcp/categorylist/designer/ahkah
And of course Japanese website (where you can find all their stores' addresses):
http://www.ahkah.jp
I don't know about UK, but here in the US, a lot jewelry stores offer upgrades, this is an advantage of buying from local stores I guess.