Living in outbuilding temporarily

[mads]

Hello all,

we have had planning approval for a full knock down of existing bungalow, and rebuild of a 3 storey house plus car port and garage. 
 

separately, and subsequently, we have had planning approved for knocking down 2x existing garages to replace it with a new 10m x 6m insulated steel outbuilding (4m at apex). Needed full planning permission as it is 0.5m from boundary (to neighbours field)
 

we were originally thinking to live in a static caravan on site whilst the rebuild is done. However, this isn’t seeming very feasible in terms of then removing it, as well as the fact we would need to create hard standing, get electricity to it, water and sewage. 
 

we are now thinking that perhaps we build the outbuilding first, move into it for temporary accommodation whilst the main house gets built. We would look to put up some temporary stuff walls to separate spaces. Once it’s built, then will return it back to single space outbuilding. 
 

questions:

1) do we need planning permission to live in the outbuilding?

 

2) what things do I need to consider for building regs sign off (assuming would need)?

 

3) I assume it doesn’t affect the VAT reclaim for main house which is a separate planning application and did not mention the new outbuilding nor will include in terms of materials, costs etc. 
 

thank you