I'm pretty security conscious, and was lucky enough to have a friendly local fabricator make up some door security bits for me. I couldn't really find what I wanted so knocked-up a design, gave him the lock, and he came up trumps. Took a few weeks as he's always busy, and did bits at a time whenever he could, but only charged about £120. Pretty good value considering that's all the materials and fixings, including the 1.5m 20mm stainless bar.
The lock is a serious bit of kit, and Machine Mart currently sell them for about £63. The lock box has a protruding lip to make it very difficult to get access to the lock at the necessary angle with a drill bit.
The workshop is also a separate zone of the main house alarm, which has live bell boxes back and front. Outside sockets are isolated when not in use. Hopefully it's all enough to make it just too problematic for any low-life to bother with. If they still fancied a go, hopefully my mate next door will point his 12-bore at them for additional discouragement :twisted:
Hope that helps, but if I ever lose the keys I'm f***** :mrgreen:
Cheers
Stu