They claim to have received funding from the Arts Council.
This does not suggest that they're reputable or useful, or that their advice will be good.
I've skimmed through their website and see nothing terribly impressive there: they're one of many organisations offering editorial advice, and most of the organisations offering such advice won't help you in any significant way.
If you want to use an editorial agency (and although it can be useful to do so, it's not required if you want to get a trade deal), then there are others I'd recommend, like TLC, or Cornerstones, or the Writers' Workshop.