nicktick

We've just started today on the trench for a permitted development single story extension. And we've just come to the conclusion stupidly late that we should of applied for planning and gone for 5 metres instead of confining oursleves to the permitted 4. This would negate a lot of steel & pillars to create a recess to enable us to have a bit more room in the kitchen. But we don't want to hold up works now - so are having a sleepless night about whether to revert back to 4 metres or apply for retrospective permission when its all done. Or indeed just keep our heads down & come up for air in 10 years when we are clear of restrictions. Not sure what the implications would be when we sell and move on though. We are not overlooked, so wont affect neighbours (one is a massive tool BTW) And we have trees on his side approx 14 ft tall. Totally new to all of this so any thoughts very welcome!