Rear extension cost estimate

[321pastamaker]

Just starting on planning a rear extension. This will involve knocking down existing conservatory and building an extension of 5m x 5m. Want to create an open plan kitchen diner, not sure if that will be big enough or if we will need to reconfigure existing space. If we take existing space into consideration we then need to remove the external rear wall and an internal wall. I realise that there are many factors in such a build, but for anyone who has recently had a rear extension how much have you paid? We are in London which I know will add to the cost.

We've recently had an extension. Similar to yours- removed conservatory, 6x6m extension at rear, reconfiguring downstairs including putting up some stud walls and creating a new utility and shower room - total cost was £70k. We're in expensive part of SE.

We're knocking down conservatory and adding 9 x 6m extension. We're in expensive Home Counties and all in (as in all the fittings and extras) will be £85k.

Thank you @Mummyshark2018 and @sparkla, helpful to get some ideas of cost.