Taken the liberty of a couple of minor alterations now the event is past tense.
Also replaced republic in last verse for independent because Megs would otherwise have no chance of being a queen. That ok Jim?

Royal wedding (Jim McLean)

I once was a lady who knew her own mind.
I stood up for women and all of mankind.
But along came Prince Harry to make me his bride
So I knelt down before him and swallowed my pride,
    With a toorali oorali oorali ay.

I didn’t have to wait for a passport like some,
Prince Charles just whispered a word to his mum
Who spoke to Theresa and they all did their bit,
They Windrushed me a passport so now I'm a Brit.
    With a toorali oorali oorali ay.

My wedding it cost just a few hundred grand
For horses, policemen and soldiers so grand.
And some of the public they got an invite,
But brought their own picnic for money is tight.
      With a toorali oorali oorali ay.

No tax on our bedrooms, you pay for our rent,
No mortgage or gas bills, not even a cent.
And soon there'll be babies, one, two maybe three.
I won't have to worry for EVERYTHING'S FREE!
With a toorali oorali oorali ay

I'll never be Queen, there're too many up front.
Camilla and Catherine, both in the hunt.
So maybe I'll move to a wee Scottish glen
For Scotland will be independent by then."
      With a toorali oorali oorali ay.