It is true, there are hand car washes all over that offer washes from as little as £2!! They will also carry out a full valet for £15+ (quality not necessarily guaranteed!!!!)
There is one in particular that is local to me that operates from a pub carpark. No overheads as such and there is always a long queue!
I do not think any business paying for an operating centre, especially a newly established one, could compete in this market.
If you do go ahead be mindful of drainage. As I recall you will require an interceptor tank. This is another thing that the guys on the pub carpark won't have. They must be operating outside of the law on many counts but no one seems to want to stop them.
You caould always report every car wash in your area and hope they all get closed down.................
Best of luck