Household insurance also does your bike cover. And no stereo, TV, computer, CD/DVD collection etc?
Yes, I realise this about the bike but at £150, it's not a no-brainer, not given my relative risks and costs etc - may be ideal for the OP.
Re possessions, I do have the items you list but a beautiful 2005 28" Trinitron tv costs £20 these days, the laptop is £150, or £300 new, a quality amp and speakers on
ebay is £100. Like everyone, most of my items' worth is in what I paid for them rather than future utility (dreadful old Oasis cds, Titanic dvds, breadmakers etc). I'd have contents insurance in a minute if I lived in a higher risk location or owned my house cos I'd want carpets, curtains and something to sit on, cook on etc.