I too had a Defender 110, for over a decade. Whilst I loved it, I would caution that they are stupidly expensive to run.
This comes down to two issues: chassis and engine: They are built to rust The factory chassis is full of holes and crevices and things like the outriggers under the firewall/bulkhead drop off for fun (because of rust), as does the rear crossmember. Both faults are MOT failures, as is rust in the middle crossmember (found on 110s), or aluminium corrosion around that one, because it takes the middle row seatbelt strongpoints You can get aftermarket dip-galvanised chassis which ought to be better, but expensive and time-consuming to fit (and you need heavy lifting gear and a LOT of space in the workshop).
Engine: there are a variety of styles and sizes. I doubt there are any left now, but DO NOT BUY the original Turbo Diesel (TD), nor allow anybody to give you one, nor accept one in part exchange nor allow any part of one to get withing 200 yards of your vehicle (just in case). They are slow, unreliable and thirsty.
I don't know about the very recent ones, but of the British engines, the TDi (AKA TD4), is probably the best - willing, not complex, reasonable torque (0-60 without needing to re-check the calendar), and quite efficient. I had one as a donor from a Discovery - there is a fairly straightforward conversion. TD5s are common, but they are the start of the increased complexity that is the bane of modern engine designs, and although "better" spec-wise, possibly not as good a buy as a TDi. TDi will also run on chip fat and cooking oil (yup really) - later engines won't.
A few more thoughts:
Tyres: the ex-factory wheels were steel, huge, heavy and thus not fuel efficient. The corresponding "Town & country" tyres have shot up in price - in the early 2000s they were 25 quid each as farmers got through loads of them. Now probably 150-200 each wheel. If you mount the spare on the back door it will probably wreck it because of the weight. If you put it on the bonnet, (a) small people (i.e. drivers) cannot see out, (b) you risk decapitation if the bonnet stay doesn't lock properly when you are looking under it. A supplementary frame to take the spare at the back is a good idea, but it can restrict the back door opening.
Wiring and secondary systems: "Joseph Lucas, Prince of Darkness" says it all really. The best idea is to scrap the factory system and wire the vehicle properly for positive and negative, for all but stuff that must be grounded to the chassis. Most of the switches - lighting, indicator stalk, horn,etc. are rubbish. Rear light cluster faults can be hard to diagnose, beyond, "yes, I know it hasn't got 12V." There are several dozen possible points of failure in each circuit. If you have a rear door window heater, or a wiper fitted, those are reminders that through it all the factory maintained a sense of humour
The cabin heater is legendarily inefficient, although this can be fixed with some effort. Even so, best to use the middle row and rear for shopping trips to Iceland in the winter, as no human will survive travelling in those seats for more than around 2 miles.
Factory fitted "sun" roofs and the curved "alpine lights" along the top of the sides of County pack vehicles are best thought of as sources of fresh water in a crisis. I never stopped our sun roof from leaking, nor raining inside the vehicle in the winter because of condensation - gaffer taping bubble wrap to it can help, but make sure youcreate some sort of gutter along the back edge, or drive with a wide-brimmed hat on.
Aftermarket "just like the originals" parts, especially doors, are to be avoided, as they are actually made in India (I think) and don't fit. I bought some new front doors, but never got round to fitting them. When I included them with the vehicle I thought I was being helpful, until the purchaser (my specialist Landy mechanic) showed me - the actual skins didn't line up with the rest of the steel frames, so they were junk.
I loved my Landy, but therapy has worked, and the craving has now gone. My wallet is much happier too.