myrrh, while Google wants to ensure that landing pages are relevant and useful to users who've clicked on AdWords ads, we don't expect every keyword to be used on the landing page. So long as your pages are clearly relevant to the topic you're advertising, you are providing valuable and unique content, and that the nature of you business is clear to users, its probable that your landing page quality will be fine.
In the past I have suggested using the "How would I feel if I landed on that page?" test. In this test, you make a concentrated effort to forget everything you know about your business, and put yourself in your customer's shoes. Search on one of your keywords, perhaps even feeling a bit excited to be looking for a product or service that you really want and need - say for your mother's birthday. Then, take a close look at your ad through the eyes of that customer, to gather some information about how you feel about the business which says they have what you want. Then click on your ad, and visit your site.
Once there, how do you feel? Take a look around. Are you comfortable with what you see? Would you trust that business with your home address and your credit card information if you knew nothing about them except what you see there?
Bottom line, what do your consumer's instincts tell you? Are you ready to buy, or are ready to leave?
All that said, here's some info from the AdWords Help Center which may prove to be useful:
How do I create a high quality landing page?