Don't put it in the toilet cistern. That's the first place they look and it ruins the battery anyway. Instead, try the cupboard under the stairs, nobody will find it there.
I didn't want to open a new thread just for this question, so here goes..
Will it be detrimental to the battery if I take the bike out for a couple of miles whizz round the block without fully charging the battery? I'm assembling it tonight and I just can't wait!!
no. The battery has LVC protection, when it runs out of juice, it shuts itself down. When they are made, they are loaded with 50% charge. You can do about 20 miles before running out of juice.