I have an under counter built in oven, which had cooked a million pizzas for teenagers - and it had got very greasy. Give her a ring and tell her what you want - I am sure you can agree something.
Just thought I would share that I have just had my oven cleaned, by Abigail at Spotless Cleaning - first time ever, after putting it off for ages - and it has come up looking like new. Abigail is on 07565508849