The U.K. CAA initiative on carriage of ADS-B equipment by GA aircraft should be congratulated as a major move towards GA safety, data collected is pointing towards this becoming a viable basis for affordable anti collision system.
The use of non IFR approved GPS is covered by label in the transmitted data indicating the quantity of the GPS.
One can only hope that EASA will show a little more flexibility when it comes to enabling ADS-B equipment , especaly well known and certified IFR systems that require an STC for each airframe Type , this makes high quality ADS-B installation prohibitive for Aircraft that don’t have an FAA type certificate.