cv19 certificate

That is probably because the UK cant cope with testing ........... in the UK and there is no reliable antibody test available.  Very very few are being tested for the live virus.  I believe that you can get a Covid-19 test in Kenya for around Ksh 10,000.  I have never found the British high Commission particularly helpful, to be honest.

"so yet again  kenya is behind the ball"  I love the way expats are so quick to criticise Kenya and the way they run their affairs. 

Regarding Covid, the UK is so far behind the ball that they're not even in the ballpark.  It's a mess and Covid-19 is rife.......... I have had it, so has my family.  Are you sure you want to come back right now?

Regarding the Certificate of No Impediment.  It isn't Kenya's fault that the UK no longer issue the document and why should the law change because the British have decided to change theirs?  Plenty of countries do and it is probably why Kenya ask for it.

I married my Kenyan wife in the UK and we just had to get the documents that the registry office insisted on, which was both irritating and tricky, but the law is the law.  It's about respecting the law of the country you are in, surely.  If you look into it, Kenyan authorities will be satisfied with some other means of legally endorsed evidence that you are free to marry.