In which case since it doesn't say class 2 equipment I would say that those lights you highlighted from toolstation are not compatible with your non earthed lighting circuit.
If you do eventually find compatible class 2 led downlighters then to wire them you need the examine your current ceiling rose to ensure that a line and neutral is available and if necessary put the into terminal blocks by following these guidelines which you may have seen before.
http://www.diynot.com/wiki/electrics:lighting:rose
Then the new lights are connected to the L and N as shown and then looped in and out of second to the third as you suggested earlier.