hi Alison...I also faced this dilemma when I bought my B max...I fitted ford roof rails (at great expense) and roof bars (as recommended from the on line ford companies that you can fin through Googling) and Thule bike racks. The system works well. The rails are relatively easy to fit...took me a bit of time but straight forward) and I'm happy with the result...... The only gripe I would have is the price...but I scoured this forum and contacted another company that offered a cheaper system but decided that I was going to the keep the car for a good few years so i could justify the expense.
I see you live locally to me. I was going to ask Sandicliffe in Loughborough to fit the bars for me but they were going to charge £750 for the bars, rails and two bike carriers inclusive of fitting.
Good luck with this...the only other issue to think about is the height you need to lift the bikes up...I do manage...but its a long way up. opening the back and front doors helps in fitting the bars and lifting the bikes.