Have had a few flights on those kind of days, one recently was particularly bumpy, was hard to maintain headings and accurate heights for long periods, particularly in the vicinity of the Chiltern Hills. When I used the R/T I must have sounded a bit weird cos mid sentence the a/c would hit some turbulence and I'd sound like I'd just been punched in the chest! All in all, even though bumpy flying can be a little unpleasant it is good to experience this weather cos when you have those really smooth days, everything will feel even better!