Health Control Card

[Happy28]

Hell All,

I have received a Block Letters, which is like a post card addressed to Health Control Unit, Heathrow Airport, from Heathrow Airport the first I landed in UK 2 years ago, which is 2010. Since at that time I didn't live in UK, and I didn't have permanent address, so I never mailed this "post card" out. Now, I decided to live in UK permanetly and has the permanent address, so there are couple questions I guess some of you guys may have answers for me:

1. What should I do with the Block Letter, or "Post Card" with my information filled in ? Should I just mail it to the address printed on the back of card:
The Principal medical Officer
Health Control Unit
Terminal 3 Arrivals
Heathrow Airport - London
Hounslow, Middlesex, TW6 1NB

2.What will happen after I mail it out ?

3. Will it any problem if I mail it out after 2 years since I received it ?

Thanks so much for all the helps here !