I have had to use my side door a few times, mainly when there has been a power cut, I can then still manually open the door from the inside. I have a Yale key code entry on the side door so even if I lock myself out I can get in there and use the key safe to get a new house key out. Works really well, the door talks to you and you can set one use only codes if someone has to have access.

Even if you plan not to have a side door, get the builder to add the lintel and block it so you can add one later if you feel you need it. Saves cost now and later. I found that upvc with big windows gave a lot of free light, I also added non opening windows to give light but security.