U.K London, where can i buy the two different types of Carbon Monoxide testing kits?

Question

WARNING
If you have or smell a Gas leak, the emergency Gas Telephone No. in the U.K. is owned by National Grid. Their employees DO NOT CARRY CARBON MONOXIDE TESTING KITS. So you may still be at risk.
All gas appliances, should have a flame that is blue in colour. If there are any other flame colours, it means other poisonous gas chemicals including carbon monoxide are present, and should be switched off and tested by an independant qualified corgi appliances. person. Alternatively phone British Gas.
Did you know That National Grid is only legally liable upto the gas meter. and even then legally some meters are separate.
Installation is legally separate, as are appliances to be checked. National Grid carry out visual checks and if gas is smelt the equipment or the mains is swited off.
There appears to be some legal liability loopholes that all people renting accommodation, and customers with gas appliances including central heating systems should know

Answer 1

im so glad people are making **CARBON MONOXIDE**,aware,
thank you

Answer 2

Dont bother with the changing colour spot ones - they will change colour but what good is that unless you are watching them 24/7, plus they aint gunna wake you up through the night. Get one with an actual alarm, if you are on a british gas contract or you know someone who is then you can buy them from your engineer. otherwise go to b&q and ask, i think they put them near the smoke alarms.
(Anyone living in rented accomodation should have an anual inspection arranged and paid for by the landlord, done by a corgi registered engineer)

Answer 3

Not sure where you reference to "two different types"...?
Normally, you just install a Carbon Monoxide Detector.
Those should be available at your building centers in the UK, but if you prefer online, these guys have it: http://www.carbonmonoxidekills.com/codetector.htm