Radar Control Service...i.e. you fly what headings and altitudes (s)he tells you to.
Yeah. It's pretty easy. Just follow the headings and altitudes given to you, and maintain VFR at the same time. This means you should tell the controller as early as possible if the instruction is going to take you into cloud so he/she can plan an alternative route for you.
Also, once I was outside his zones he told me to freecall London FIS. I'd expected to stay with him for the duration of my flight so I wasn't expecting this. Did he just want me out of his way do you think ?
Once you've left the sector you'll be passed onto someone else who covers the adjacent sector. This is normal.