First of all I really hope that that's a post from the real Nicola Sturgeon.
First of all your states are wrong. 89% of the UK is white British, of the 11% that are either black, Asian or mixed race plenty of them are second or third generation immigrants - which makes them British by pretty much everyone's standards.
I wouldn't argue there are "too many" immigrants, the UK can take quite a lot more - and will need to if we want to beat Germany to that largest economy in Europe by 2050. However we have had very high levels of immigration over a short space of time and the infrastructure hasn't kept up.
It's widely accepted that immigrants are net contributors to the economy but whilst they may be funding the extra doctors, schools, trains ETC improving these takes time. For every 10 families that turn up in Boston you don't get a new primary school classroom or new GP for instance. Immigration needs to happen at a level where the infrastructure is given time to play catch up. Even if immigration has been to high - don't blame immigrants for overcrowded hospitals and schools, blame the politicians who encouraged them to come but didn't have foresight to invest in roads, houses or hospitals.
You've then also got to remember that immigrants take time to integrate too. There is a tendency for immigrant groups is to live with each other, talk in their native languages, not get involved in the excising community. This isn't "rudeness" or unwillingness these things just take time. If I was an immigrant in another country, I know at least to start with I would gravitate towards English people (certainly English speakers) because I would be nervous. However if you have high levels of immigration you end up with communities divided along cultural lines, not mixing ETC. You need to give arrivals time to become more involved into the existing community before you bring more people in. Otherwise you get division and people don't just fail to integrate they don't want to.
Immigration doesn't have to be a problem and when problems flag up as a result of immigration it is very rare its the immigrants fault. It's normally a cock up somewhere else along the line, a politician who thinks you can encorouge mass migration whilst you have over subscribed schools and a housing shortage. Regardless in the UK we need to reset the immigration debate, we used to accuse people who raised legitimate issues as racist; now we talk about nothing else and its getting boring. The most important thing to remember is that immigrants are people who were simply born elsewhere. This means they arent social pariahs NOR are they glorrious and beautiful people who can resolve all our problems.
