So currently I have a T30 which I hope is repairable, it's not then I need a replacement car which i would start with looking at the T31.
I need to tow a 5 birth caravan 1445kg unloaded and a small trailer for tip runs and general moving stuff but not both at the same time!

Looking at both manual and automatic in diesel just wondering what is the best model of engine to what I need to do?

I haven't towed with my manual T31 as haven't had it long ,it's the 148hp one ,I have a trailer full of rubbish for the tip next week though .I haven't seen any auto models about more than 148hp, but manual models seem to came in both 148hp or 170hp so you would have a bit more help with towing with the 170hp model .I am sure someone with an auto who tows regular will be along shortly. I would say the T31 will be better than my old 06' T30 dci though just by the general performance and handling of it while driving at the moment anyway ,will let you know

Diesel
automatic 150hp 1350kg.
Manual 150hp 2000kg
Manual 170hp 2200kg.

I tow a small trailer with my diesel auto T31, mainly for taking stuff to the tip, but I also tow a caravan. My caravan is an old one though, which tend to be lighter. It weighs under 1,000kg laden and my X Trail barely knows it's there, so I often find myself checking the mirrors to see if it still is!

Incidentally, that small trailer is a nightmare to tow, as I can't see the darned thing and I can't feel it on the back either.

But i have towed like 2tons with the auto

Doesn't surprise me at all to be honest. The way mine tows 1 ton it feels like it could cope with far more, easily. Nissan don't seem that confident about their auto box, which does rather surprise me. It is a huge difference in the towing weights between the auto version and the manual.

I am looking for the auto side of things because my wife can only drive automatic so then we can have 2 cars to share and my left hip is starting to give me gip so being up and down the box when towing the caravan is making going away not too much fun!
I know when I was looking for my current x trail I spent weeks looking for a diesel automatic to then discover they didn't exist in the T30!

I had exactly the same thing! I was looking for a diesel automatic for ages before I realised that they weren't available in T30 versions. I'm glad I finally found just the T31 I was looking for though, although it did take me over a year. Nearly two in fact. I too have a bit of a dodgy left hip, probably from all the gear changing I did when I drove coaches for years! They were nearly all manual boxes back then.

I wanted a diesel for towing my caravan, and I haven't bought a manual box car since back in the 80s, and I didn't have that one long before going back to automatics. I got my first auto back in the early 1970s, and I'll never go back again!

I find that I arrive more relaxed no matter how far I have to drive when driving an auto and dont have the constant worry of is my clutch ok

Looks sadly like you're going to be out of luck if your van is 1425 as you'd be over the limit for the auto sadly at 1350kg. Although it would tow it you'd be bu66ered for insurance. Can't think why it is so much less than the 150 manual and can only be down to the auto box; same with engine tune limiting 150 to auto's.

I can tell you the clutch on my T31 Facelift is incredibly light. Last week my son borrowed mine in snow to get his partner to work for EAAA. I ended up with her 2010 Audi A3. The clutch on that gave me leg ache!

Not long after buying mine and before it was tuned we hired a car trailer to collect a BMW 530 my son had bought but needed some work for MOT so couldn't be driven. Car weighed in at just under 1600kg and after a few calls I managed to get a trailer that would take the weight and still come within limits - trailer weighed in 500kg with winch. I hadn't had the car all that long so it was good to get used to this long trailer behind when fetching the car - approx 60 miles. Car loaded easily and after making 200% sure it was strapped down off we went. Firstly I was shocked how easily we moved off and after about 5 miles I felt comfortable with this big load behind me. It drove incredibly well and at no point did I find it worrying. Only downside was car delivered around 32mpg but cruised easily at 50. So it's worth considering as I'm sure others will have a light clutch.