all you have to do for a BACS OR STANDING ORDER is to give them your account details, i put mine on the completion slip i leave or hand it them and explain it.
If they want to BACS it over every time you clean they just go in to there online banking system and pay you
or they can set it up as a standing order, ie set amount on a set day to your bank, ie £15.00 on the 16th of every month
direct debits can be done thru company's like gocardless, all you do is register with gocardless, you get your customers email address send it to gocardless along with the customers name and gocardless send them an email with a link for the customer to send their bank details to gocardless and every time you clean you notify gocardless and they notify the customer and the money is withdrawn from the customers account and paid into yours
In my opinion the problem with gocardless is that the customer has to answer the email and provide details just like the customer i have,who has taken two weeks to answer her email.
There are company's, who for a one off fee, will also do paper direct debits, ie you have a DD mandate fill it in at the customers door and email to the company, fast pay is a company i am looking at
good luck