A great read - a couple of (hopefully) constructive comments.

This is clearly a UK aimed guide, perhaps better to include UK examples rather than almost entirely Battlebots (aka US) examples of robots. You want to enthuse people, and familiarity with UK teams for examples would make more sense

The BEC advice appears to contradict itself, starting by suggesting people don't use the BEC in an ESC, and run a dedicated one - but your wiring diagram then removes this and uses the ESC. FWIW to keep thing simple, using an ESC BEC is probably best. Also perhaps worth noting that you might not want the BEC active in both ESC's ?

On page 12 the charging guidelines also appear to contradict, first suggesting that most people will ask you to remove batteries for charging, later this changes to 'its essential you charge in a fire proof bag'. Perhaps remove the comment about some people asking you to remove them - and just stick with the best practice of taking them out, visually inspecting them and charging them in a LiPo sack.

Up until page 13, the guide has appeared to work well across weight classes, but on page 13 it suddenly heads towards a featherweight guide as the motors section only covers drill motors, RangleBox and VEX. Perhaps it's worth making clear what motor would work in which class of robot, and also something covering heavier weight class requirements/suggestions ? Or if the guide is aimed largely at the Featherweight builder (which continuing to read it would appear it is), perhaps consider making that clear from the start.

A really good document though, a great guide for someone considering starting and once published something that we'd love to share with the schools that we work with as a team !

Ed