Hello maxie
Presuming you are sole trader and not a limited company then you should be ok with the minimum wage issue as advised.
The minimum wage is really only there to protect individuals from exploitation and i don't really see any problems with an individual not being penalised ie being able to claiming tax credits and at the same time only earning £4 per hour say if they work for their spouse. Some self employed family businesses simply take alot of effort to earn very little.
You may also be required to provide evidence that the the work has actually been done as for example if the husband is a taxi driver the tax office is not likley to believe that there would be much spousal work needed for this type of business.
Unfortunately i am not sure what your exact question is in relation to the section below so you may need to rephrase it slightly.
but he wasn't able to tell me but I have discovered in their manuals under the 'remunerative work rules' that as long as a person is actually 'paid' for the job, payment can even be made in 'kind', and for self-employed, work must be done 'in expectation of payment' but this does not necessarily mean 'in profit'. Of course the 16hrs a week rule must still apply. Can anyone clarify this for me?