Good deal lag. The HAlfords kit is actually quite good. I think the thule "quick fit" clamps for the roof boxes are much better though - with ours you have to screw on locking nuts etc to secure it to the bars.
We bought thule bars for our Lag as Halfords were doing a deal and they were slightly cheaper than their own.
We alsobought a Halfords onw brand roof box - one of the longer thinner boxes - so we can still fit 2 bikes on top as well.
The rear "reflective" Halfords sticker came off nice and easy - the two side mounted ones didn't.
A trip to the local surf shop in town saw me return with 2 "surfy type" stickers which nicely covered the halfords ones.
We have used the box 3 times now, once in France & twice in this country - it has been great. Driven through some heavy rain and the box stayed bone dry inside. Fuel economy was not unduly affected considering we had a fully loaded car,roof box on top,one bike on top and three bikes on a rear carrier we still managed 45mpg on the French trip overall.
Nice idea about the tow bar lag.
My wife is also keen to get a caravan and i too am reluctant to fit a tow bar.In principal I quite like the idea of having a "shed on wheels" but don't relish towing it/storing it/maintaining it etc.
I have made a wooden frame and attatched it to the roof trusses in our garage. I just lift the box up in to the framework and it sits there quite nicely without taking up valuable floor space for the other junk. Just have to be careful not to "walk" into it as it hangs down from the ceiling.