For deposits? Do a search for some suggestions, including getting pre-paid cards topped up.

It would be a sexual service, but outcalls mean it's not a brothel (or if it is, you're not in control of it!) That leaves the control for gain laws, so if you want to avoid a slight risk of those, say 'If you want to see me and Ms X get it on, you can book her too by doing...' i.e. leaving the arrangements up to the client.