Don't panic!
I've just looked at the specifications of several Airflow mattresses, such as this one:
https://www.apollo-ht.co.uk/product/apollo-5-premium
They all have a power rating of only 12W. (Other makes might vary but probably not by very much). Running one for 24 hours would use 24 x 0.012 kWh of energy = 0.288 kWh.
The price of 1 kWh of electricity (at my address and using British Gas's Standard Variable tariff as an example) is 29.24p, including VAT.
So that means that the daily cost of running the pump is 0.288 x 29.24 pence, which is about 8½p. That equates to about £2.50 per month.