Not sure what other practical and realistic options remain
There is an alternative if controversial POV: fly on your own devices, in Class G (or Class E), without any ATS service.
That's what mostly happens in UK Class G already. Only a few pilots call up London Info. With modern navigation, it's pretty effortless to just zoom around the place.
And if everybody had a Mode C transponder, anybody who spent money on TCAS would see them (no need for a radar service).
It isn't realistic to navigate around the London area without having to break off from LARS to get ATZ transit information/clearances and local movements
You are not under any abligation to call up a Class G airfield unless crossing their ATZ. And if you do, what can they tell you? They are mostly A/G radio so can tell you about their own circuit traffic, that's all. And if you have a GPS you can avoid all the ATZs easily to start with.
I never call up anybody unless I can get a meaningful service, and to me that means radar. A FIS is not worth the radio work, for what one gets out of it .... "13 aircraft known in your area"