Knock down walls and redo small kitchen

I'm based in SE London and in the process of buying a small flat. It's a conversion, so the kitchen is crammed in and quite small. We would like to knock out two small walls and refit the kitchen, as there's no oven, and it doesn't have a full-sized stove or refrigerator. We would like to save costs where possible, so are considering Ikea cabinets and building them ourselves before having them professionally installed. I'm wondering what I should expect to pay to remove two small walls. Will I need an electrician to make plugs for appliances? Also, what could I expect to pay for cabinet installation? It's a tiny L-shaped kitchen about 2.8m x 1.75m. Thanks!