I would always fill the tank to stop any moisture in the air corroding the tank from the inside, but add a stabiliser / preservative such as Frost's POR15 product
http://www.frost.co.uk/automotive-tanks ... -pint.html
Either put the car on axle stands or over pressurise the tyres by about 40% to reduce flat spots.
Give the car a good wash and wax.
Store the car in a garage. All our storage facilities are dehumidified and we leave the car windows down to keep the interiors dry.
The Carcoon products (which we sell) work very well and there is an outdoor version available too, a Size 4 which would accommodate the Excel would cost £500 inc VAT and delivery.
Change the oil and filter to get rid of all the contaminants.
Use a battery conditioner or trickle charge the battery periodically.
You could slacken the drive belts too, just depends how far you want to go and whether you want to run the car periodically. If you do, don't run for less than 15 minutes (to make sure you get rid of all the condensation in the engine and exhaust) and don't leave unattended and at idle as the iol pressure will be at it's lowest. Vary the engine speed between idle and say 2000 rpm.
Good luck with the hibernation !