Clarion, apologies for coming to this a little late -- have been away on personal stuff. Let me offer a few observations & suggestions on Dealing With Bugs'n'such, daily mileage, and diet. I'll preface this by saying that I've not done much hiking or cycling in UK, but I do have a lifetime's worth of hiking, camping, cycling and paddling in Canada/North America, Europe, & East/Central/Southern Africa. On a six-day hike of the West Highland Way in 2008, I encountered midges, sometimes lots of 'em, but they were more of a nuisance than anything else.
1) My main line of defence against airborne biting insects is clothing: longsleeved shirts closely buttoned a neck and wrist; long pants closed at the ankle; and
especially a headnet. The latter is available with more or less fine mesh, and the best ones have a toggle drawstring closure that falls below your neckline. They weigh nothing, and fold up into a 2" cube. I may have missed it in the posts above, but I was surprised not to see it mentioned. The headnet shd be put on over a hat with a brim -- say, a bucket hat -- which allows the net to drop to your shoulders away from your face & head. NB: see the note below on repellants and clothing.
This line of defence is used mainly for campsites -- places where I'm more or less stationery, and there are lots of mozzies, etc.
2) Timing matters: When I was young an impulsive, I used to go paddling, etc., in the Canajan bush in early June. The magic of the changing seasons, etc., etc. After getting savaged by blackflies more than enough, I gave up. There is no defence against these brutes, material or chemical. So, I avoid blackfly country for the first three weeks or so of June. (you might enjoy Wade Hemsworth's song about the creature, here:
https://www.youtube.com/watch?v=f389hIxZAOc. "Ode to a Nightingale" it ain't.)
3) Repellants: Body chemistry varies, and my experience may be specific:
* "Skin-so-soft" felt nice on my skin, but didn't keep any mozzies away.
* THE BEST repellant I ever used came from a herbalist in Yukon. Our daughter worked on their farm about 15 years ago, and gave me some. I just checked their website, however, and they seem no longer to offer it. It's probably not an immediate option, but you may want to check the site for Aroma Borealis (nice, eh?):
aromaborealis.com. You could say to Bev that Meg's dad recommended her product, and maybe she could make you up a special batch. It's a long shot, though.
* I now use only DEET-based repellants -- but sparingly, and
very carefully. DEET is powerful stuff. If you use it, keep it away from your skin & esp your eyes -- put instead on your clothing at wrists and neck; and, on the brim of your hat above your ears. Here in Ontario DEET-based products use only 29-30% of the stuff. Do
not use DEET on nylon clothing--it can effectively melt it. I've found that DEET is, however, an A-grade fire-starter -- if your kindling is sputtering, stand well back, and squirt some DEET on it. The results are truly spectacular. (Mind you, I used 96% DEET the couple of times I tied it.) Now that I'm older and wiser, I just use birch bark...
4) Placement: It may be stating the obvious, but try to pitch camp away from standing water, and try to take advantage of prevailing winds. There's often a tradeoff betw shelter (e.g. trees) and the bug-chasing value of wind. A lightweight tarp can be a great help.
5) Daily distance: Whatever you decide is your choice, obviously, but I can't help asking if what's "doable" is the issue. Personally, I'd look for a more flexible adjective: "enjoyable", perhaps? I've found that,
over the course of a day, "slower" is often more enjoyable. One can always ride quickly, of course, but I've found that a guideline which allows for photos, chance conversations, lingering on a lunchtime terrace, what-have-you, can be more rewarding. FWIW, I use 90 kms/day (56 mi) as a guideline over the course of a tour. There'll be days when I do 60 kms, others when I do 130. The 4Hs play a part, of course: heat, humidity, headwinds and hills.
6) Finally, an observation on diet: Twenty years ago, after I had my first run-in with Deep vein Thrombosis, I looked into Barry Sears' book "The Zone Diet". I found it very helpful. He argues for a 40-30-30 balance among carb, fat & protein: 40% of calories from carbs, 30% from fats, and 30 from protein. They
type of carbs, etc., matters greatly too, of course. He has a lot of very specific recommendations on what and how. Our son was an international-class athlete around that time, and I asked him for his opinion. He said he thought that Sears' approach--based on the necessity to regulate insulin produced by the body--was valid, but in his diet control, he used a much simpler approach: no carbs after 12 noon.
In my experience, using Sears' approach
plus cycling produced a gradual but apparently profound and beneficial change in my metabolism: over the years between about 2002 and 2010, I dropped about 20 lbs in weight, from +/- 205 lbs to +/- 185. The change was gradual, and then all-of-a-sudden: I had gradually reduced my weight to about 195-200 lbs, and then in 2010 I did an 8-day tour of the Gaspé peninsula in SE Québec. When I reached home, I was down to about 185 and a bit. The latter has remained constant as my "default" for the last decade-plus. I still follow Sears' guidelines, but not as closely as I once did.
Hope that's helpful, and good luck with your big adventure!
Cheers, John