Have you read the books referenced?
With reference to those 'guerrilla training camps':-
Cronin Napoleon- ("Cadoudal ran a training camp for conspirators and guerillas at Romsey in England') his Notes and Sources for the whole 'Cadoudal conspiracy' section in Chapter 16 cites: 'Letters from English agents in Stuttgart and Munich in the Liverpool Papers.' No source reference.
Pocock Terror cites numerous page references from Bourienne's 'Memoires' but does not link them to the text. None of the passages in Bourienne make any reference to Cadoudal organizing "guerrilla training camps in Hampshire" as described in Pocock's text.
Horricks Napoleon's Elite (Cadoudal "had been running the Royalist guerrilla training camp at Romsey") has no footnotes. He lists Cronin in his very short bibliography.
Paul le Met has already commented on the relevance of Lloyd's footnotes in The French are coming. He doesnt' mention any training camps but implies Cadoudal actually ignited the bomb in the Rue St Nicaise attack of 1800, so that "there is little doubt" this "ruthless and dedicated killer" had returned to Paris to assassinate Bonaparte. Did someone mention intellectual dishonesty?
On reflection, it could be something less glamorous.
If any one wishes to consider the cross fertilisation between these authors, they might examine these four descriptions of Cadoudal :
[Cronin 1971] 'George Cadoudal, a squat, red-haired Breton peasant of immense strength_Goliath to his friends- with a bull neck, broken nose, red sideburns, and one grey eye bigger than the other…..Cadoudal, ran a training camp for conspirators and guerillas at Romsey in England.
[Horricks 1995] The squat, bull necked Breton, (only just over five foot tall) with red hair and a scarred broken nose…had been running the Royalist guerrilla training camp at Romsey' [He was described as cinq pieds et 3-4 pouces]
[Pocock 2013] ‘[Cadoudal], a heavily built, red-haired Breton aged thirty-two…. after escaping to England, he had organized a training camp for guerillas in Hampshire
[Lloyd 1995] limits himself to 'a squat, barrel-chested Breton.'
I think 'tertiary source' as a term is fair enough.
For what seems to be a thorough investigation of the subject of the British intelligence effort and support for French opponents to the Republican and Imperial regimes, I recommend Elizabeth Sparrow, Secret Service: British Agents in France, 1792–1815, which I have just found. Detailed footnotes at the bottom of each page. No mention of guerrilla training camps.