Hm, not sure. Insurance isn't something I would have thought of buying, and it actually costs more than £25 which is 10% of my order. Is the insurance worth getting?
IMO definitely. Will you be insured if you have an accident which is your fault - and you injure a pedestrian or damage a car?
How will you access legal help if you get knocked off and you or your bike are damaged - which is exactly what happened to me last year, the BC solicitors are handling my personal injury claim (I had to have surgery...).
For the sake of £8 a year once you've taken the bike discount into account. Indeed, if you pay by DD it's under £4 (a pint of beer

) Of course hopefully none of this will ever happen, I certainly didn't expect it to, but that's the point of insurance. It's only a couple of quid a month.
You may well need other things from
Halfords over the course of the year and all of that will be discounted. Do you have tools for example, a pump, bottle cage & bottles?