Cycle rack recommendations

Take a deep breath and buy a Seasucker.  It's probably the only rack you'll ever need (as long as you don't buy a convertible with a fabric roof).

Personaly id look at the towbar racks

Your not towing so dont need to have that cataogry on your UK licence 

The problem with boot mounted racks is they will eventually cause some paint damage where the feet sit or where the metal straps hook onto the bodywork

Think about it, once you attach the rack to the car then attach 2-3 bikes to the rack, the weight of those bikes is being forced down onto your bodywork

With the towbar racks all the weight is on the towbar which is attached to the chassis, the rack and bikes stay clear of the bodywork so dont cause any damage, some models have a tilt function so the boot can still be accessed when the bikes are on the rack

Only thing to becareful of is how much longer they make the car, espcially if your reverse parking

I have a bones one which carries three bikes and found it to be very good and the bikes are sercure on it. You do need to check that the rear tail gate is metal as I know that there are some vehicles where parts of the tail gate are plastic and won't take the strain of having a bike carries attached too them. (Not sure if this iss the case with your car.) Hope this helps.