Use your gas oven Peter, No 7 setting for an hour and a half, don't worry about using gas because I used my cooker as often as I do now and I used about two and a half bottles a year!
I usually Microwave for about 5 mins then 30-45 mins in a hot oven.
Lovely and fluffy inside nice and crispy outside.
Don't want to risk running out of gas as I didn't organise a spare bottle yet.