I do work for three letting agents as well as normal domestic work, my nephew works for two and gets most of his work from them. We do not do any other cleaning work, cookers or the like. And we charge them our normal rates. The problem is getting in with them as prev mentioned. You have to be persistant, not too pushey and be lucky. I got my last agent when their previous long term cleaner went bust. Get a good A4 leaflet to give them and see lots of them. Remember not all estate agents do lettings, so you may have to contact a regional office. I like the work, as generally there is no furniture to move, so jobs times can be quite fast. Oh and be prepared to wait about 4 - 6 weeks for payment.