As Barjon says the discrpancy is because youre comparing the current market price to the spreadbetter guess at the price in June.
Usually the major cause of a big discrpancy in the prices will be a dividend due between now and then.
In this case it looks like a divididend is due on 2 June so thats probably the reason.
You are forgetting to factor in the risk-free interest rate between now and then too,, this will currenty have the effect of lowering the future price.