I'm not sure what you are getting at in your last post - a commentary that things are tight when one is trying to run as a self-employed person, especially if one has to lose some the gross income because the main contractor is a 'deemed employer'?
I don't want to be teaching GMs to suck eggs, but are you and your partner familiar enough with how the CIS operates? In that, if HMRC regards the organisation that he is contracted to as a deemed contractor, then most operations that relate to the construction activity, including many operations like fabrication off-site are tied into the CIS. Which I think means that the contractor is forced to deduct a straight percentage off gross wages - irrespective of the claimed employment status of the self-employed person. But your partner seems to be an SE site manager - I'm not sure the extent to which this job spec is covered by CIS - my guess is that it is.
Not do I understand whay you are trying to do in this 2 week period between contracts.
Does this help?
http://www.hmrc.gov.u...tro/decide-if-cis.htm