The employment laws in the UK are somewhat liberal compared to our European neighbours, you’ll find that in most cases having the right to live and work in the UK will suffice for most jobs, unless you are looking to join something like the armed forces.
If your girlfriend is a UK citizen I think you can get a citizenship after you’ve been married to her for 3 years, might be worth tying the knot. Marriage to a UK citizen is the quickest route to citizenship as far as I know. Citizenship will also mean you don’t have to worry about renewing your visa every few years.