I'm not reading this, spread betting tax advantages will swallow any alpha you will find in the futures market
Turnover is the actual money going through your account - so you might sell a put for 20 but have to buy it back for 30, but you roll it and take in 40, then close that out for 15. That is the simplest options trade I can think of! Try explaining strategies to HMRC and you will be arrested for heresy.
Not at liberty to say about comms- but it's really nothing when I have an old fashioned phone broker who works orders for me -often to market makers. Online my choice is Saxo or IB and Saxo don't even allow spreads