I was talking with magnatom about making and selling jerseys like these in the UK, unfortunately we both became fairly busy and nothing has come through. I do however still plan to make at least 2 jerseys, one for Silly Cyclists and one for Cycle Camera TV.
In relation to your question. I don't know of any UK sellers, and I would advise not getting something like 3 foot please, as that is less than the minimal passing distance suggested by the DFT.