cost of putting dormer window in attic + extending kitchen.

Hi everyone I'm looking for a rough cost of

1) putting a dormer window in an attic that is already converted with velux windows. We want to replace the veluxes with a dormer about 2m wide.

Would like tiled roof but flat is ok if significantly cheaper.
Also would like to insulate the rest of the roof - can this be done from the outside, putting stuff under concrete tiles?

2) extension to kitchen of 30m square, two walls already there and can be used, want flat roof with slylight, and will cost the windows and doors myself. Any ideas roughly?

It's a 1950s semi in Dublin.

Thanks!!!