Added special paint (to match my Aero - vanity rather than sense), have added the Intercom (but not sure what I'll do with it) - just in case, Immobiliser (should pay back through the insurance), chrome pack (prefer it), black exhaust shields, build record, tonneau (mohair).
Standard leather (black, no quilting) - like the quilting but it doesn't seem necessary with black, no stickers (can always add these when stone chips or whatever come along).
However, on reflection, if you might not be keeping for a long time, probably best to stick to the simplest spec you can. The options are unlikely to add their cost to the value as with most cars in my opinion. But may make the car easier to sell.
Tried to add heated seats but factory said power supply is not up to it.
Allon White seem to have some rather natty extra headrests on a demo car which is for sale, plus the boot rack (15Kg max I believe). I expect some fitted luggage sausage bags will turn up soon to make the best of what's available in the boot.
BHM do a foot-locker which makes good use of the space at the end of the passenger footwell.
There are some nice retro leather tool-bags which will probably fit under the cowl with some heavy duty velcro or similar, and I think this may be worth adding.
Oh - and AA relay or similar seems a good idea if you get a puncture...
Most of all, it's a bit of fun, so treat yourself! Some options can be added later but some cannot without a lot of hassle...