"So your rebuttal is that you think "not well" means they actually speak it well enough to become full members of society "
No it was a rebuttal of your point because you said that 22% of women never bothered to learn English when they came to the UK, in fact it was 4.5%. But again you fail to accept nuance, those who do not speak it, or do not speak well are increidbly likely to be the older generation who arrived here as adults and have found it more difficult to learn. You also rant on about integration not working and attempted to use this to justify your point whilst ignoring the fact that the vast majority of the population speak English well ( 78%) and the huge majority speak it well or at least have some (95.9) which shows a huge attempt to integrate.
"not well" may be enough to engage in society, yes, how many UK nationals have very low literacy rates?
"Is it prejudiced to say that it appears like the values of many Muslims who are already in the uk appear incompatible with our values ? "
Yes because your are highlighting one group, there are many groups of a vast array of ethinicities including white British, who's values are incompatible with the standard set of "British values".
You make sweeping generalizations about "muslims" and integration, using statistics in a deliberately disingenuous way in attempt to prove your your point, and hold exceptions up as the norm.
It doesn't prove your point, at all, but does prove something else.