I think organized tours are a great idea if you have the money. I can't comment about which tours are best for you because I live in America and not sure what's available in UK area.
Level of support quite honestly is whatever you feel comfortable with, if you don't mind packing your own tent and gear which is called self contained touring then that's the cheapest, Self Contained means you bring everything on your bike including food but it's shared carrying of food and cooking gear and you have to cook it usually by share duties with other riders helping to cook and clean up; you must be able to fix your own bike although if parts are needed some may have a van supported mechanic with supplies; this type of tour has a leader with preset camping grounds arranged.
If you hate camping then going from inn to inn is the better way but it's also the most expensive they have everything you could possibly ever need and no worries about cooking out or cleaning up etc.
In between those is where you have a van or fully supported trip that carries all the gear and when you get to your designation they already have the tents set up and food going, they also have SAG support, but you must have your own tent and camping gear it's just that they carry it and set it up for you by they time you get there, and you need to know how to fix some things but especially flats you'll need to carry the stuff needed for that repair and know how to fix it, for more complicated repairs they'll have the SAG and the SAG will carry more tires and tubes if you need them.
There are a lot of inn to inn tours in Europe but not a lot here in America, most people here who want a more luxury tour will do a combination of using motels and sleeping outside. I have heard of some tours that went from motel to motel and were part of a fully supported tour that had a combination of camping and motels so those who had the money could stay at a motel and eat out while the others in the tour camped out nearby.
No one can tell you which is the best tour, it all depends on you and what you're comfortable with doing and how much money you're comfortable with spending. So I suggest you search and study the internet, then study the various bicycle touring companies in your region and see what tickles your fancy.
