Back from my trip and I thought I'd report back on the recommendations. Predictably I got sidetracked into various other places and didn't make everywhere recommended but really liked those I did. So
I went to the Cafe Savoy a couple of times and agree about the breakfast. A nice relaxed start to the day. I also went once to the Cafe Narodni across the river and opposite the National Theatre. That had a more old fashioned atmosphere that I liked.
The Tradice Andel was nice. Very similar to the Urquell bar opposite the Spanish Synagogue which I used to be one of the places I visited regularly. I also went to a place just found the corner which I liked and did unfiltered Gambrinus - http://www.smichovskaformanka.cz/. The only downside was it was a bit smoky when full.
I really agree about U Kroka. We were lucky to get a table and next time I'd reserve. The rabbit was excellent and everything else was very good.
I liked the Old Staropramen bar. I think it's a nice modern take on a traditional bar but I also remember it as it used to be and find the change a bit disconcerting!
Finally the Kozlovna was the place we went to most often. The people were friendly and we just felt very comfortable there. Definitely somewhere my friend who lives in he Czech Republic said he would go back to now he'd found it.
So, many thanks for all of those. In return if you fancy something a bit different I can recommend the Midgard Bar - https://www.google.co.uk/search?q=midgard+bar+praha&rlz=1C9BKJA_enGB728GB728&oq=m&aqs=chrome.3.69i60l3j69i59j69i65j69i57.2480j0j7&hl=en-GB&sourceid=chrome-mobile&ie=UTF-8#fpstate=lie - it's apparently a must go to for metal heads (whatever they may be!) but everyone was very friendly to us fogies. More importantly they serve unfiltered beer from a craft brewery which was both good and cheap. Sorry, can't remember the name of the beer but it was a name from Irish mythology.