Tour of the UK - Advice required

andrewkennedy70

live in France.  Next year I propose to tour the UK with a caravan+car.  I am looking for some good advice on 1)best time of the year - I could take 30days + for the tour. 2) A suggested route taking in as many tourist sites/exhibitions/gardens and in particular
old country houses and estates i.e. the like of those owned by the National Trust.    If anyone out there has experience of such a trip......I would appreciate any info.