Hi Mike,
Can you physically mount a 235 tyre on a 7J? Yes but this is dependent on the manufacturer. How the tyre fits on a wheel is a bit more nuanced than just looking at the size.
I personally wouldn't do this, homologation issues aside (i assume the UK has approved sizes like we do in Italy), you're likely going to ruin your ride quality, throw off your speedo readings due to the diameter differences and it's potentially unsafe.
If you absolutely have to go bigger, get some wider wheels too. If necessary, keep the F-Sports for winter tyres or sell them altogether.