Without you reading the terms and conditions of the policy it's impossible to say whether £40 for a sum insured of £1000 is good value or not.
It might represent good value but less so if the terms and conditions read that the kit had to be under a year old.
It's your policy, not ours. Read it and make your own mind up. When doing so, consider two things in addition:
1. How likely are you to significantly damage your kit in a spill of your own making?
2. In the event that your kit is damaged by a third party in an accident, there is a very good chance that their insurer will be paying to replace / repair your kit, not yours.
Last but not least, some (by all means, not all) Household insurances would cover clothing and equipment under an All Risks extension to the policy, though you might like to check the excess and the precise terms and conditions.