Another Person in a Post-Trump Panic...

You absolutely do NOT want him to overstay, that could lead to a ban of up to 10 years and WILL lead to failing the good character requirement for Indefinite Leave to Remain and Citizenship.

You absolutely want to play by every the rule.

And then there is the Immigration Act 2014 which ended free NHS amounst other things and the Immigration Act 2016, which turns immigration crime into criminal with jail time, for those that help them too. Even driving a car in the UK when not meant to be here, is criminal with jail time.

The thing about working in London is that of course it's more expensive, but the salaries are much higher and there's way more jobs.  I'm sure Dundee would have a lot of good things going for it, but if you actually want to live in Brighton or near London you should be able to afford it based upon a software based salary.  Especially if you work as well and you didn't mention kids, you should be able to live pretty well.