As a pilot, VFR in France, who flys quite frequently in your country, I accept what ever service is given by ATC, without specifying any level of service myself.
I find a huge difference in service, for instance nearly nothing from Paris Info, to lots of in flight info from Seine, and Lille Info.
I also find French D class zones very helpful in giving zone transits.
Your explanation that ATC gives service corresponding to the airspace goes someway in explaining the above variation, and validates my habit of accepting what is on offer.
As to your question on FIS request in Class E, perhaps let the pilot know they are identified on radar, maintain lookout, and maintain VMC would clarify things to them.
Conflicting traffic info gratefully accepted.
I expect you will also have to remind some of the VFR levels to fly, having heard some Brits transmissions last weekend.