It is a shame that you never did strength training before and during your rugby career. As you know now strength training prepares us for other activities. But then it's never too late to start. I did not start until age 66.
There is a SS coach in the UK but I think only one. Check the Resource section. At minimum a consult can be invaluable.
If you can get to a Doctor that might be advisable but be aware there are still many Doctors that advise against strength training for anyone over a rather young age. There reservations are usually based upon nothing.
You may wish to post some videos if you have access to the equipment needed.
Best wishes to you.