do it. do your research, it's hard to get in to and sells out in minutes.
Oxfam - i'd be keen with a strong team.
Cradle - they have accepted Hounslow Classic ultra as a qualifier two years ago so you should be fine there. And yeah, it sells out within like 5 minutes.
Cool thanks guys, it looks like an awesome adventure!
Make sure you plan some rest and recovery in there too, and good move putting some of those races in the diary for future years - no point burning yourself out. Fine if you just want to run them, but don't expect to race all of that and perform.