Jen
As I found to my experience a lot of dog ramps are quite heavy, I have one here you are welcome to borrow indefinitely if you know of anyone travelling up towards you that can fit it in there car.
I have two, one very sturdy rigid plastic the top slides over the bottom half, with carpet covering it for grip, very heavy but very robust, I also have a less sturdy one that folds in half made of wood with grooves in for grip.
I have to say with the oldies that come through here they are invaluable as like you trying to lift a dog in and out the car leaves me in agony. You are welcome to borrow either if you can get it up to you.
Failing that if you can make something up for the time being I am coming to Kent in April and would be happy to meet up with you then