Aylesbury Circuit and GPS

After a cold misty morning the sun broke through about 11 am, so after an early lunch I set off on a new ride I'd planned. The temperature was cold, about 5 or 6C, but warmer than it has been, with no wind, so quite pleasant for cycling. I took an anticlockwise route around, but avoiding Aylesbury, from Tring to Wingrave, Whitchurch, Waddesdon, Stone, and Weston Turville, a total of 34 miles over 2.5 hrs. Unfortunately my feet got quite cold in the last half hour, so it looks as if a single pair of socks isn't enough for my new shoes. The soles of my feet were the coldest, so maybe adding lambswool inner soles might help, although possibly an extra pair of socks and overshoes would do the trick.
I've also been contemplating getting a GPS for a bike, such as a Garmin, but can't justify spending at least £300 one one, when my bike didn't cost much more than this. Also as I'm long sighted I'm unable to focus on my handlebars without reading glasses! Normally I just stop at a junction, get out a map or phone and put on my glasses. I'm normally happy to have a short break anyway.
I've been playing around with an iPhone app I've had for a while called The Complete National Cycle Network - by Sustrans. It allows you to download maps for free to your phone, so if you don't have a signal you can still use offline maps. Of course the iPhone GPS doesn't need a phone signal so you can pinpoint where you are. I tried downloading 1:150,000 and 1:50,000 scale maps, but found that the 1:150K maps were adequate and clearer. The 1:50K maps don't seem to give you many advantages, apart from a few street names, rivers, more detailed woodland and houses. There are no footpaths on them, so you can't use them for hiking, like you can the OS ones. Also the 1:150K maps take up less space, and you should be able to fit the whole country on an iPhone - so they should be good enough for next year's trip to Lands End. Here are some examples with the 1:150K on the left. You can also plot routes, track your existing route etc.

Just discovered if you zoom in further to an urban area you do get a map with all street names marked. So it's probably worth doing this for major towns.