Just went to log onto First Direct and they have a similar deal to the post office they will give you £100 prices start from £5 per month and you can cancel at any time and the money will be in your account within 8 weeks. So you can make around £90.
Only downside is you do need a first direct account for this, but they will also give you £100 for switching if I remember correctly.http://www.firstdirect.com/insurance/life.shtml
*To qualify for the cashback you must be a first direct 1st Account customer. You must apply for a first direct Life Insurance policy between 1 and 7 September 2008 and go on to purchase the policy. The cashback amount will be credited to your first direct 1st Account within eight weeks of the policy commencing, providing the policy has not been cancelled within that time. The offer may not be used in conjunction with any other offer. first direct reserve the right to remove or vary this offer at any time without notice. Premiums are dependent on individual circumstances and underwriting criteria will apply. first direct Life Insurance is underwritten by HSBC Life (UK) Limited.