Hi Shafig,
FJs & BJs are as you rightly said are in short supply in the UK but there are a lot more around than nowadays.
First I would recommend looking at French ebay or similar as they still have plenty of BJs however many of them require some tlc but it's not too far to go and see ones that interest you, but they'll all be LHD.
America: rebuilt/restored FJs (they only ever had a handful of BJs) tend to fetch top dollar and then you have got to ship it and go through all the import stuff but then that applies to all and to a lesser extent includes the European sourced vehicles.
Oz trucks are RHD, which may be important to you. OZ ebay. Several members on here have imported from there and they will probably be able to guide you. There are a number of Oz members who may be able to assist, particularly once you have truck in mind but rarely are things just round the corner there.
Costa Rica may be worth a look.
I think you have to decide the model you want e,g, trying to sleep in the back of a 40 series is not possible if you are over 3 foot tall. If you want to camp in it maybe a HJ47 / troopy would be better. Obviously the BJ engines do have greater longevity and parts are more available and economical but if oodles of torque is your pleasure the the F2 engine but 15-17mpg is the best you'll get.
Bottom line - if it's an pristine FJ that does it for you then the USA is the place to look but if you want a RHD diesel the look in Oz.
Flesh out more of your specific requirements and I, and others on here, can maybe point you in the right direction.
One thing though, decide first exactly what you want and then find it - we looked at all we could find and travelled the length and breadth of the UK to find ours. Importing back then wasn't really an option. When you get nearer to viewing we can advise you of the areas to check - specifically for the dreaded meal worm and then places to get your parts from.
Hope that helps, oh yes, and welcome to the club.
Regards,