If you want to grow Garlic you should be putting it in soon before the cold weather is gone.
www.seedaholic.com is an Irish mail order seed supplier with lots of detailed growing information for each variety they sell.
If you have access to B&Q they do a Vegetable Garden 12 Pack of seeds for about 6 euro.
If you have limited space then you should try to grow high value crops and experiment with varieties to find the ones you like. Also google Intercropping, Successional Sowing and Rotation.
Hope this helps :-)