Google maps has "measure distance" function. Select a location such as Calais, right click and you can drag a dynamic line which measures distance. One night, with a glass of wine by your side, you might enjoy exploring how deep past the UK coast an Me 109 might. I count the Me 109 range getting to about 10% without drop tank and 20% with. Bombers past that point would be intercepted by Hurricanes unhindered by Me 109. Fw 190 had slightly more range but not much.
For some Bizarre reason the Luftwaffe didn't push to install wing tanks in the Fw 190 until it was too late to manufacture them but the ones designed added enormous range.
The Luftwaffe can send bombers over London at under 10,000ft protected by FW 190's as close escort and 109 stacked up as high as you want to go, they can be that brazen because the Hurricane can't deal with that. With London ablaze the Luftwaffe doesn't have to go any further, all it has to do is isolate and let England wither on the vine, as far as drop tanks go you can get DT fitted to 109's and 190's quicker than you can get a Spitfire replacement in service.