You will just need the switch and a relay like this one that fits into the fuse box!

 

http://www.mgf.ultimatemg.com/group1/info/mgf_history.htm for the Spark specification (in brief) No hardtop mentioned so it is likely the h/top you have is an extra. You will probably find the "connector" to the "missing" switch is behind the centre console. The heated rear window switch is not common on e-bay (there is one at http://www.ebay.co.uk/itm/110775478860?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 - as you can see, they tend to be pricey!!
Try http://www.rimmerbros.co.uk/Item--i-GRID000069 for a new one from rimmers - you could also add the relay mentioned by Spaceoctagon.
If stuck, don't hesitate to ask any more questions.:beer:

 

It's incredibly easy to do, fitting the switch and relay. You will need the small black relay not the yellow one. The relay fits in the only spare socket in the fuse board ( under the steering wheel) with wires behind.

The wiring for the switch is already behind the centre console. Or just behind the electric window switches. If you remove a few blanking switchs you should see it. It's then just a case of plugging it in to your new switch and shoving your relay in. Job done!

The switch will only work with the engine running though.

Good luck!!

 

Thanks for all your help guys, been really helpful!!

 

MGFMania fitted a rear galss window and a heated rear screen with switch which I realise is likely to never be used as the car hibernates every winter! Dowh!

 

Is the same relay etc for an MGF rather than a TF?

 

Different switches and relays, sorry.

 

You have a PM philb88

 

They are good to deal with and most likely will have the switch you need.