Active job

Cut square hole and build Access door in Concrete Ring of home 2

I have a 1950's house in Paremata. I want to cut a small square access hole through the concrete foundation at the front of the house, to make going under the house accessible. We ultimately want to insulate underfloor, so there is an extended job here. But simply just need a hole cut and perhaps a door made. There is access from the manhole in house in the back of the property but the house is at its highest point off the ground at the front and we feel for the future this would be a good idea. I would need assurances of the following: *Will the foundations/house still strong after the cut ? - Can there be a support frame that goes in. * This is all ok by council ? - happy to pay or get anything inspected (go through with the notions) here.