You can buy a locking wheel bolt removal tool from anyone that stocks the Draper range of tooling or they would order one for you if not in stock.
Last year I happened to lose the removal key for my 18" Azev's on my Fiat Coupe,

I was panic stricken until I got hold of this to remove the wheels, You actually get 2 sockets in the pack as most locking bolts only come in 2 sizes.
The socket is tapered inside and cuts a lefthand thread which gets tighter due to the taper as you screw it on, it took me approx.45 mins. to remove all 4 wheels bolts. Panic over and blood pressure returned to normal.

Cost is £12.50
Jim.