Is there any recommended minimum on the controller and receiver that I can tell if my nitro car controllers will be no good?
The rules state what sort of frequencies are allowed for specific weight classes and they have to be UK FCC complaint off the top of my head. 2.4GHz is the norm though.

so ideally i’m looking for 15v+ to be comfortable and as for the batteries thats something ive got to learn for definite
Though a factor, I'd not worry too much at this stage about voltages and so on though the more you know, the better prepared you are. It definitely go through the rules for fighting robots (http://www.fightingrobots.co.uk/docu...uild-Rules.pdf) and it'll start to make sense as to what is allowed and what isn't.