So I read about this technique on this here forum, seems to really help. I get less warping and in the event the raft has begun to warp I can kill the print before I waste more plastic.
I'm not sure who the original credit goes to but thank you.
I have one small addition which you may be common sense, but I haven't read it here:
when you re-start a print if it has been idle for too long it will take a second to push out its initial bit of filament. This means it misses the first 10cm or so on the resumed print, to get around this if you unload and then reload the filament before you resume it will be primed and ready to go.
Above comes with the caveat that my hotend might be in worse condition than yours and you may not actually be having this issue at all!
p.s. For those who haven't seen this, it simply involves adding a pause at 0% to allow the raft to root itself down to the bed.