Because people are playing weekly, and paying up front in varying amounts, startin playing at various time and we have to take off prize increase notionally monthly net is not a measure used as it's not "banked".
Possibly the simplest way is currently a net after fees and prize increase, and £5 lucky dip we have £183 net each week. However, we currently have £8,885 raised. Ot of that the weekly £50 prize increase, (currently £1,150 jackpot to pay out if it's won) and £5 per week Lucky Dip commitment. However, the majority of Lucky Dip winners have generously donated their £5 back into the pot.
Hope that answers the question sufficiently.