Sorry if I posted a blank just now!
Thanks wandgrudd and Dunnyrail for today's comments - very useful. It seems I should go DCC route. I presume if I turn sound off via DCC controls loco will then run silently on DCC if I want (eg when running on friend's DC line). The said dealer knows me and would set up loco for me (he is experienced LGB repair agent). I think, because he knows me, he suggested MTS3 as a simpler and cheaper way in to DCC. I am now slightly worried about whether I need a PC (computer I presume) as, after my ancient PC laptop died recently, I bought a Mac computer because of friends recommendations as to it being a more stable and secure (I am going to gave to bite the bullet on online banking too) system. But who knows - I don't. I have a simple android Samsung mobile phone and am considering a cheapish Samsung tablet to buy. Would either of these work with setting up MTS3, I wonder, if a PC is really necessary to do this.
I live in Finchley, north London. My 32mm garden railway is live steam and battery loco (with and without radio control) operated. No track power needed. All very straightforward, control wise. However, iver the years, forces beyond my control have made me buy LGB and some other G scale locos and I currently gave a very small indoor layout - but can go visiting. Might build a small 45mm garden layout but hoped from house move out of London obviously now on hold.