When I was learning, I used a pair of hike boots that I knew were comfortable for exactly the same reasons as you. On my Mod1 I bounced a bit (details elsewhere) and the hike boots definitely stopped my ankle actually breaking, but I bashed up my totally unprotected lower shin quite badly. I tried a lot of different styles, some really bulky and some not so. My only real thing was I knew I didn't want zips - crud builds up in them and then they jam and then they break. I finally settled on
these which are available from lots of other shops too. They're pretty light, I can wear them on the bike or walking around, they're just velcro to fasten and they are long enough to have saved my shin if I'd been wearing them at the time!