Is it worth installing solar if my roof faces east and west, not north?

Yes, in most cases. East and west-facing panels make less power in total than north-facing ones, but they produce more in the morning and late afternoon, when many households actually use it. With feed-in tariffs now low, using your own solar is worth more than exporting it, so an east-west layout often works well. A battery can also store afternoon power for the evening.