What kind of table do you have? That might make a difference.
You might need multiple layers of 100% batting with a piece of fabric like duck fabric covering it to make it safe to use on your table. If you have a few old towels you can use instead of batting, that would probably work, too. Use painters tape to secure them in place at the edges of the table, with most of the tape placed under the table. Duck tape would work well for temporarily securing the ironing pad to the table, but the glue may be difficult to get off of the table.
Alternatively, go out and buy a piece of plywood and have it cut the size you want it. Cover it with several layers of batting and a nice heavy weight, iron-able fabric and secure the batting and fabric in place. Make sure the back of it will not scratch the table - maybe put a piece of fabric over it, too. Put it on the table, use it and then put it in storage for the next time you need it. Of course, that assumes you have a place to store it.