I haven't done any work in Purbeck for a while so cannot comment on that particular council or their green belt policy although they used to be a nightmare, but over the last couple of years neighbouring authorities have dramatically tightened up their green belt policies. I had one recently where a modest pitched roof on a existing double garage was refused due to specific green belt policies (even after favourable informal feedback from planners) whereas about 4 years previously I had a large 2 storey extension approved relatively easily on the same property although it contravened the exact same policies. The joys of dealing with our wonderful planners.
In this case I would be inclined to go for a re-submission first, specifically highlighting the existing and proposed floor areas to verify your 38% claim. I can't be bothered to read Purbeck's policy but most seem to allow up to 50% increase so I would study the Purbeck policy and act accordingly. In worst case possibly consider pushing front of extension back slightly as the hall and landing look like they could afford to be trimmed slightly. If that fails then I would probably go to appeal.
Finally, without causing offence the drawings aren't great and aren't doing you any favours in providing a clear illustration of how the proposal meets current policies. Chappers mentions "emphasis the good design" above but I'm afraid I can't see it, just looks like a typical boring generic 2 storey box you can find on any housing estate up and down the country. I would have thought your designer could have presented it with a bit more flair and possibly given some context with the adjoining property, it could be a detached dwelling from the elevations and floor plans.
Good Luck
In this case I would be inclined to go for a re-submission first, specifically highlighting the existing and proposed floor areas to verify your 38% claim. I can't be bothered to read Purbeck's policy but most seem to allow up to 50% increase so I would study the Purbeck policy and act accordingly. In worst case possibly consider pushing front of extension back slightly as the hall and landing look like they could afford to be trimmed slightly. If that fails then I would probably go to appeal.
Finally, without causing offence the drawings aren't great and aren't doing you any favours in providing a clear illustration of how the proposal meets current policies. Chappers mentions "emphasis the good design" above but I'm afraid I can't see it, just looks like a typical boring generic 2 storey box you can find on any housing estate up and down the country. I would have thought your designer could have presented it with a bit more flair and possibly given some context with the adjoining property, it could be a detached dwelling from the elevations and floor plans.
Good Luck