Hi

Converting from manual to auto is no feat to be sniffed at. It's complex time consuming and can be expensive.

You'll either need a new radiator with the auto cooler part or a secondary cooler radiator.
All the wiring loom will need replacing (auto boxes use different functions)
You may need to move/add some gearbox mounts, I think the Autobox is longer than manual box.
Transfer box may be different so that'll need replacing.
Gearbox tunnel may need modifying.
You may need a conversion plate to fit the box the engine
You will need to re-register it at DVLA (Big fine if you don't, although not a hard job couple of forms and hey presto it's done oh and a small fee)

I looked into converting a 109 Series to an Auto and found it was far cheaper and easier to buy an auto as standard. There is a way round it take one Range Rover V8/Diesel with an auto box fitted slot the lot in with loom/rad/transfer box etc. (although not a cheap option it might be easier)

How about a Range Rover ? It has air con, autobox, lhd and cheap.
Hope this is some use

Charlotte