House footprint on Outline Planning Permission

[MG-Wales]

Hi,  my partner @er-wales and I are thinking of buying a plot of land in Wales that has outline planning permission for our self-build project. The planning permission is for a 4-bed detached house, which is what we want to build. The approved site plan shows a 10m x 6m rectangular footprint but it also states that the house can be a maximum of 12m x 10m on plan. This is only on the plans and officer report, but the maximum size doesn't appear to be on any of the planning approval conditions.

We were looking at different layouts and because of the irregular shape of the plot, we were thinking of an L shaped ground floor which would be less than 120sqm footprint but would be 12m in each direction. We’re also thinking of having some areas of the first floor as a cantilever to provide some shading to the big openings on the south-west elevation which would make the house as viewed from the top 14m long. 

Has anyone got any similar experience with planning regarding house size stated in the OPP and know how likely the planners are to accept a dwelling with the same footprint area but with a different overall dimensions?

We were thinking of getting in touch with the planning officers before buying anyway, but wondering if anyone has had a similar experience before applying for the reserved matters?
 

[nod]

It’s quite normal For full planning the planners require a design 

If the seller intends selling the plot on There no point in risking being rejected 

If a max of 12x10 is stated 

You can work your new design to those dimensions