There are some restrictions but most of them are common sense. You cannot register trademarks that are:
a generic description of the goods or services offered under the branding (for instance, you cannot register the word ‘tweed’ if you are a tweed manufacturer but you could register ‘McInley’s Tweed’); * offensive
misleading
insufficiently distinctive
Before registering your trade mark it is advisable to check, via the trade marks database, that it hasn’t already been registered.