Should be easy. They just push down and click into place.
All isofix is really is a couple of metal loops below the seatcushion. The child seat clamps to these loops rather than a seat belt.
Have you purchased your car seat yet? If not, then consider a Kiddy seat instead. Seehttp://www.kiddy.de/gb/startseite
They are now available in the UK. We have one - the Kiddy Comfort Pro which is suitable from 9 months all the way through to 12 years. They are fantastic and much safer than a conventional UK seat where the child is strapped tight to the seat back. So quick and easy to put child in and strap in - takes about 5 seconds. Our daughter is 2 now and we've had the seat just over a year.
On my car there is a "Isofix" label sewn into each side of the outer rear seats, if you fold the seat base or poke your fingers into each side ofthe gap at the base of the seat back you will feel the steelattachment loops. As described in the user manual.