I'm intending to use a twin Girling mastercylinder set-up, and was wondering if SVA requires a level sensor for the brake fluid. If yes; how can I realise this in a Girling integral reservoir mastercylinder?!?!?!

You definately require a level sensor (and dash mounted level warning light)
If your reserviors dont have swithches, you will need some that do,

Hmm, I was afraid that I would indeed need it......(it does make sense).
Any suggestions?

Try BGC Motorsport. You will find them on the web.