Brass knuckles are illegal here in the uk too, but I've got a nice steel one that I picked up from a pal in the US. I used to take it to work when I worked the door, but only as a last resort if my own life was in danger and/or facing multiple badass opponents and I needed a 'one shot' hit. Thankfully I never needed to use them in 10 years, but it always felt better knowing they were there.
Obviously you might get arrested for using them, but it would be preferable to death/serious injury. They are definately not easy to use, better over a glove (which you might be wearing on the door anyway), and you should practice on a bag regularly. You can be creative too, hammerfists, normal shots, raking blows, etc.
As for the brass shins, I always wondered if you could get those titanium plates fitted that surgeons use when people break their shinbone. Once you had recovered from the surgery there would be little or no sign of them surely? Although you would probably be banned from MT or MMA competition if your secret got out.
