There are two aspects to this: trade mark law and copyright law.
As long as you are not intending to sell any of the products which you include on the website, trade mark law shouldn't cause any problems. Trade marks are only infringed if they are used in the course of trade without the authorisation of the registered owner (or his licensee).
The copyright part is slightly more complicated. Copyright won't apply to company names, but it could apply to some graphic logos (artistic works) and to any photographs of products. Generally this won't be a cause for concern provided the companies involved are likely to benefit from the exposure in your directory. And indeed even if it was your intention to rate or review the products in a fair manner, using both the logo and a picture of the product alongside the listing could be justified under the fair dealing exception for criticism or review
. However, great caution needs to be exercised in where you source the photographs of products. If they are definitely the manufacturer's own publicity photographs then you should be fine, but avoid using photographs which have been taken by third parties, such as wholesalers or other traders, as they may well object to your using their photographs in a manner which won't necessarily benefit them and may even compete with them. In such cases the fair dealing exception is unlikely to apply. The safest approach is to take your own photographs if this is possible.
You don't mention how you intend to assemble the data for your directory, but you need to aware of something called database right which protects the work (or more accurately, the investment) involved in assembling databases made by other people. To take an example which is unrelated to your project, say a review site was set up to rival TripAdvisor. They would need to collect the reviews and database of venues, locations etc from their own sources, and couldn't just take great chunks of TripAdvisor's database and re-package it. If you think this subject might affect you, you can read up on database right here