To be honest I'm a co-host myself in the UK and I don't understand how they have structured their figures @Greg306
what they should be telling you is
1. how much they think you can charge for your listing
2. Giving you a cleaning fee that is recharged to guests
3. what commission they charge for their service
what they charge for restocking etc
cleaning and linen fee should be recharged to the guest
do make sure you only use a management company or co-host that puts the listing in your name and that contract has a notice period if either of you want to give notice if you are not happy with how the relationship is working
For example
3 night stay @ £ 100 per night ~ £300
agency commission say - 20% - £60
net £240
less Airbnb commission (which varies slightly)
have you checked comparable places in your area to see what they charge ?
have you checked on Airdna to give you an idea of occupancy rates in your area