Home and Bargain sell a small folding step.
It is meant to be used in kitchens, but would be ideal for you to put your feet on
OK, so it doesn't look attractive....but you could put a cushion on top.
The good points are:-
When not in use it would fold up and slide under your chair.
It would do the job.
It is cheap £2.99.
It would be a good temporary solution until you found something more pleasing to the eye.