Whilst I don't have the depth of knowledge of others here, I did use the spring Long Itch as my first 'tour' in 25+ years .... and to add to the fun, used the Brompton.
I could have used the regular bike with rack and mahoosive panniers, but decided to see how minimal I could be and have the advantage of easy multi-modal transport options.
Firstly as others have said, to do a practice run with others is a good idea. Me and Mrs FF did this zillions of years ago with a weekend in Kent before 2 weeks in France. Something like the LI weekend is perfect. If you forget something or something doesn't work there are plenty folks to help-out (laugh at your misfortune) and share experience.
I was also surprised how little kit I really needed (and how much I still had).
I ended up with 15kgs of kit in 2 large saddlebags. The front mounted bag contained most of the 'Camping Kit':
Large Trangia including kettle (I couldn't find the small one)
Plastic plate, metal mug, knife fork spoon, 'Camping knife'.
Washing liquid, small scourer, sugar, tea bags.
Meths, lighter and Matches
Alpkit Hunka Bivvy bag (for extra warmth)*
Tarp, shock-cord and pegs
Small foam 'kneeling/sitting' mat*
2 season down bag
Coleman 5 reed inflatable lilo-thingy*
Head Torch
Bog Roll
Phone charger
Rear Saddle-bag:
Spare cycle shorts, cycle jersey, spare socks
Craghopper trousers, T-shirt, North Face travel shirt, light fleece, Sandals
Toiletries
Woolly hat
Misc bike tools
Paramo compressed is a Waterproof in a dry-bag
Seat-post Rack:
Vango Banshee 200
My second trip on a real bike and panniers was much the same except I brought a small low folding table to keep cook-stuff off the ground.
The * items are bits that were far more useful than I expected. As Kim says, comfort at night is hugely important. The cheap and cheerful Coleman reed bed (like an small old-fashioned lilo, is both comfortable and insulating and takes little space. It is a bit of a pain to inflate and deflate however, but that's a time issue. The kneeling mat aids getting out of a small tent without kneeling in the dewy grass. The Hunka bivvy is light, compact and adds extra warmth for little space, weight or cost and helps protect the down-bag.
For cooking a Trangia works just fine, it has all you need, is simple and reliable for basic camp nomminess. I've since moved to a Pocket stove with the Trangia Meth burner and an Alpkit Myti mug for cooking/heating duties and a Tifoon for eating just to save weight and space further.
Having discovered Merino this also cuts down on the clothing weight/space too.
I would say with hindsight that a slightly bigger tent would be better for several days away. Whilst I can get all my kit inside comfortably AND the Brompton, you can't sit upright in it. Getting dressed is quite an energetic work-out, however it is cosy and I like the side openings.
Just do it!
