Hi again Dave,
You probably already know, NATS and the CAA are pushing Low Power ADSB (LPAT) on 1090 MHz, though at present there are no units commercially available. An American company has just started advertising 'the first commercial unit designed to UK spec', but they don't seem to have a U.K importer yet and no news on price either. Also if you have a transponder, one or other of them must be switched off as you are not allowed to transmit on 1090MHz from more Han one transmitter on one aircraft!! Hence the benefit of a 'carry on' PAW which detects 1090 and also lets you be seen on P3i.
Depending on which settings you have chosen in your PAW, you might want to tighten the filters later, but the wide settings will get you used to the system quickly. Just a hint, if you are getting lots of bearingless target (mode C/S) audio alerts, you might want to turn your volume down until you shorten the detection range as they can otherwise get a bit overpowering.
Regards
Peter