A lot of key cutting places here in the UK get all arsey if you bring your own blank to be cut with no programming involved, they seem to want to sell you the blank and programming service at vast cost, oh, and they'll cut the blank too
Indeed.
Timpson at Tesco Aldershot branch could not supply a blank key for my X1/9 door locks and suggested that I found a blank key elsewhere.
I did just that via the internet and when I took the 2 blanks to them to cut, they refused outright, saying that they could not guarantee the finished key as they had not supplied the blank.
I did what I should have done in the first place and went to my local locksmiths (KBO Locks in Aldershot, and yes really, read the writing on their van!). Not only did they cut my keys but they had the blanks in stock too.