Thanks for all the info and feedback about your experiences Channa, it's interesting reading and really useful - my life circumstances are such that fulltiming is looking like a very likely move for me at some point this year, out of necessity rather than choice. I'm excited and fearful at the same time about the prospect, and have mulled over some of the problems / issues you have commented on.
The longest I've been away in the van was 4 weeks and I loved it but admittedly it was early autumn, the lowest temperature I experienced was 4 C so not particularly cold, and I had very little rain during those weeks. Although I had given laundry some thought, I hadn't really considered the real practical difficulties. Having checked launderette prices, I am staggered that a self-wash and dry is not far off a tenner per load. So that makes it only a very occasional option. So it's made me realise I need to think about more of such practicalities.
Also your point regarding the amount and bulk of clothes has given me food for thought too. Especially if some sort of "working" clothes will be needed as well as my own everyday stuff, and also a smarter outfit for interviews, hatches / matches / despatches social do's etc. For 4 weeks I managed as I took enough and relaxed my standards slightly so that some things that would normally be washed after one day, would be worn twice. But as you've said, it's very easy to let standards slip too much... I always knew that I would be going back home to a washing machine and woodburning stove to dry clothes in front of so I didn't really give it too much thought. Although as a matter of routine, I do tend to go for practical clothes which will do in several different situations eg quick drying walking trousers with canvas hiking boots / shoes which are equally suitable for a dog walk aswell as a drink in the pub or shopping or most other every day activities. But the problem of bulky winter clothes is a good one which I will need to consider further together with general housekeeping (or vankeeping) - like you said, I've learned that I really need to give the van a really good clean out ideally weekly or at least fortnightly when in full time use - easy when I'm going home after 2 weeks and can plug into mains elec to hoover it, and have plenty of hot water to give everything a good wash, and can wash and dry my bedding, and also the dogs, easily enough but when on the road, I will find that more of a challenge.
I have more or less come to the conclusion that if I do full time, because my van is not a coachbuilt with good facilities etc and is still little more than a mobile tent, I would need some sort of lock up for storage not only of some stuff from the house (paper records, some sentimental stuff, some sporting equipment etc) but also for seasonal stuff (winter clothes for example), and for temporary storage of stuff whilst on the road (craft supplies, market stall equipment etc) and so I would really need to be able to access this fairly regularly. Therefore, location of storage is important, and it may well not be anywhere near where I am currently living in northern england. So some idea of roughly what part of the uk I am going to be in is important and I really need to have a vague plan in mind, instead of just getting into the van and seeing where it takes me.
I will need to think about how often I will have to do a mail pick up from the nominated postal address so it's location will be important, and I will probably have to rely on asking friends to take my post for me. Or else I drop out of the system completely, which I am also giving serious thought to and doing research into just how possible this is.
Looking forward to hearing more of your experiences and stories - your thoughts on an oven, for example. Budgets and finances, unexpected costs, what is the minimum weekly amount you have been able to survive on and how you managed, other unexpected problems, your thoughts on full timing in uk versus in france - would like to know more.
As some people have alluded to, throwing away after one use would not be an option for me. Even just one shirt in a charity shop can cost £3 or £4, so this wouldn't work. I can see it might be necessary if you were very wealthy and living off a motorbike but not otherwise 
