Working in ones house is not less than ideal - it's possibly the most stupid and irresponsible thing any amateur pyro could do. When working with energetic materials, you should only be putting yourself in danger. Working in a residential address puts a whole load of other people at risk, especially in a terrace.
It sounds to me that you simply do not have sufficient space to work safely.
How big is the garden roughly?
Hi CP,
The garden is small, I reckon about 40 feet long by about 20 feet wide. Would a shed at the end of the garden be far enough from the house (and, as you point out, neighbouring houses)? I have no idea of what the worst case scenario is for a beginner pyro explosion. I'm not planning to be making kilos of stuff. I believe that to stick within the regs (COER) I shouldn't make more than 100g of BP anyway.