A med 1 form is based on the previous years payouts on health expenses. Eg if you sent in a med 1 form now you could only claim for the previous 4 years expenses. i.e 06 07 08 and 09. You will have to wait til jan next year for any expenses for 2010.
You will get back 20% of the expenses once you have enough tax paid to cover the refund. you will only get back from revenue what you have paid in. In other words if you paid €600 in tax this year and your health expenses were 5k you would be entitled to €1000 refund but as you only paid €600 in tax this is all you would get.