aha! Not as bad as I thought.
I unscrewed a few too many screws in my enthusiasm but got the job done pretty quickly. Bought the element off the net (www.ukapplianceparts.co.uk - part no. Fan Oven Element: Ariston, Indesit, New World #6,705.00) for £18.99 +£4PP and they accept PayPal! Original on Indesit site costs £43
Fitting requires taking off back panel, folding back the heat protective wadding, undoing 3 screws holding the element, removing the spade contacts and earth wire (middle screw). Next open the oven door and lever up the protective panel that covers the fan at the back. Old element should come out easily. Replace with new, locating the contacts in the hole in the back panel. The screw holes in the new panel were a bit big so I used slightly bigger ones.
Screw base plate on element to back panel of cooker, fold back the wadding. Refit the protective rear panel. Make sure protective casing inside oven is pushed back to the vertical and slotted into the bottom of the oven. Job done!
And if you don't undo too many screws like I did it should take about an hour (with all the fiddling about!).
Beats paying £100+ for an engineer to provide and fit.
Simon Birch, January 2007