Sorry, but could either of you explain where the £30 can be made/guaranteed?
You will need £100 in your bet 365 account. The strategy is to place a £50 back on the chelski game, then lay it off at the exchange, get a close match so as not to lose too much.
You then need to do the same thing in play on the same game, place a £50 bet and then lay it off as if it was a free snr bet. If you get the matches close enough you will come out with about £30 profit.. Because you get your £50 in play refunded if it loses. Treating it as an snr will mean you make a profit regardless.