We have a 150cm electric one. When we viewed the flat, our LL said 'I hate it, it costs a fortune to run and it makes the kitchen boiling.' This was last June. She said it was costing £70 a week. Then energy went up, and we figured it would cost £120 a week. Nope nope nope. They're also finicky to use.
So, we have a 60cm oven.
Agas run on 13amp, regular range cookers run on 35amp plus. So, if you want a normal range cooker, you WILL have to get the electrics done. That's not necessarily all that expensive to do, depending on access. We had the electrics changed where she had a 60cm oven to fit a normal range cooker; her electrician charged us about £35, now we can have any range cooker there.
Agas and getting rid of them: if it's in fantastic condition you might be able to give it away ('you must dismantle and remove), otherwise you're going to have to pay a specialist up to £400 to take it away. They're full of complicated stuff, come apart in various chunks, and are exceptionally heavy.
They're great if you have a crusty old, inefficient cottage, but don't really have a place in modern, insulated homes with today's energy rates.