My concern with the training guide is that they divide their trekking offers into levels 1-9 on a wheel chart, naming them (1-3) leisurely, leisurely/moderate, moderate; (4-6) moderate/challenging challenging, challenging/tough, tough; and and (7-9) tough, tough/tough+, tough+. But they never say what those designations mean in terms of distance, terrain, and altitude gain and loss.**
And then they prescribe a specific considtioning program for Level One (1-3), Level Two (4-6) and Level 3 (7-9), still without saying what goal you are actually aiming for. But the toughest day they prescribe, at the end of Week 6 and Week 7, is a hike of 6-8 hours with at least 1000 meters of elevation gain. I would not want to head off to what they call a “tough+” hike with only two hikes of that distance and gain. I realize their program is designed for working folks who only have time for 30-60 minutes of exercise most days, but I firmly believe the best training for hiking is to actually get out and hike.
For the OP, I would suggest that if they have not done much hiking and do not know what their capabilities are, they should find a hiking club or guided hikes in their area and get about and hike so they know their baseline. And then they can figure out what additional training is necessary, if any.
I doubt the Amalfi Coast hike is offered in summer, as it is quite hot there. The Chamonix Highlight hiking looks OK, but personally I would prefer the hotel to hotel trek, along the route of the Tour du Mont Blanc. It is tougher than the one based entirely in Chamonix, however. Also look at the TMB walk offered by another UK company, HF Holidays. I will note that both these UK companies offer the TMB in the clockwise direction, which is not the preferred route. I did not understand why until we actually did it going anti-clockwise. In this direction, you depart from Les Houches by cablecar and gain quite a bit of altitude before you start walking. The scenery gets better and more dramatic each day, and the final day, as you complete the circuit by walking from Argentiere back to Chamonix you have Mont Blanc and the Aguilles du Midi right in front of you the whole way.
**Most hiking clubs and hiking tours I have seen use a designation similar to that used by the Seattle Mountaineers, where Easy describes hikes up to 8 miles with up to 1200 feet of gain; Moderate means up to 12 miles and 2500 feet of gain; Strenuous includes hikes up to 14 miles and 2500-3500 feet of gain; and Very Strenuous means more than 3500 feet.
Looking at specific Exodus hiking tours, I see they describe the Amalfi Coast as “Moderate walks at a leisurely pace”. The actual hikes are listed as 9-11 km; in other words all would fit within the Mountaineers’ Easy designation. The Chamonix Highlights trip is described as a “3” (Moderate) with hikes from 9-15 km. They do not talk about elevation gain and loss, which makes it hard to understand how difficult the walk might actually be.