Finding PCT and Old NHS number

In my seemingly never ending quest to get legit in this country, this week we are trying to sort out the NHS/health care situation.  In 1999/2000 I was resident here and did use a surgery, once, where I was registered, in a different part of London.  I don't recall being issued with a number, but I must have been, however those papers have since been lost.

Now we would like to register and I was wondering if it would be easier to smooth the process (especially as I am non-EEA with limited time left on my current FP) by pulling up this number. I have tried calling the Find my PCT number on the NHS website, but there isn't one for my current borough and then it shuts down with no other options.  Would my preferred GP in my current location be able to look up the number? 

I can't remember the name of the practice I was at all those years ago either.

I would try your preferred GP first - they may be able to pull up your NHS number using your personal details (name, date of birth), since it should still be in the system somewhere and the number you were assigned is yours for life.

If they don't have it, they may be able to point you in the right direction/PCT to find it out.