Hi Ted,
As for headlights and such, ideally you want them to be about 3 1/2 inches in diameter, so either call Richard (at Toylander), who can supply two types....
Budget, which are Black, with a plastic grill across the lens (see my car), and go for about ?15 - ?20, or
Spun Aluminium, which are a bit more expensive ?30+, but look more like the real thing.
Check with Richard at Toylander first for up-to-date prices....
Or Visit a local Motorcycle breakers...Honda 50 / 70 / 90 'Step through's' had 4" headlights, and some of the other makes as well. Seeing as you're building a 'Defender', you could mount them from inside the wing, thus disguising the O/A diameter slightly.
If you are feeling a little flush, there are some 'Twin Headlamp' conversions for motorbikes / scooters on the market. These are in the form of a small oval 'Pod' (usually black), but I'm not sure how much they go for.
Indicators / Tail lights can be sourced from Truck / Trailer suppliers like TTC ltd. (
www.ttcuk.co.uk) or Google them, Truck and Trailer Components, Cowley, Oxfordshire.
These are 40 mm in diameter and are intended as marker lights on larger vehicles. They come in either Red, White, Amber, or Green.
The manufacturer for these is 'Rubberlite', but they are quite pricey (about ?10 each), alternatively there's always Ebay.
I managed to find some (Ebay), from a 'Shoprider' Mobility Scooter, that did the job nicely, but if you can find a Breaker / Repairer for mobi'scoots in your area, you might just be able to get them cheaper.
The only thing limiting you is your imagination (and your wallet). It's surprising just how many different things there are out there, you have to think 'Latterally', and keep your eyes open!

Hope this has helped,
Keep Busy (and looking),
Regards,
Mark.