Thank you Jonathan. I am in a gated end of road with 5 other similar homes to my original. The nearest 2 homes outside our gate look closer to the last photo. Most other homes in Oxshott look like the 1st photo. If I choose the quoins look, I'd consider using brick slips.. or.. just remove the front facing 30's style tiling and hope there is nice brick under and just add simulation quoins- they are avail in plaster/foam... I face a forest so am not looking onto a neighbor. I will consider planning permission after I decide which exterior I prefer..

Hi. Also if I don't change the fenestration but just the windows and entrance, please can you give me an idea of what type of windows would be best and entry porch?

The only person qualified to comment on the value would be a local estate agent. Build costs too are difficult, as there are so many variables. They also depend on the layout of the inside, and how much will need to change to facilitate the look on the outside. It depends on materials used, the complexity of changing the roof etc. You cannot tell just by looking at a picture i'm afraid. However, to remove the roof and do any remedial work inside plus change the facade is exceptionally unlikely to come to 100K and if it did the house would need to be cheap enough to start with to command the construction price versus selling price.

My photo is for the original house

Personally render and timber don't mix unless you like repainting every year. Timber expands and contracts leaving cracks against solid surfaces. Price depends on how much of the house you overhaul including externals, to what level of finish and assuming it's unoccupied.