In simple terms there are three type of trade marks. A word only ie NIKE. A word logo ie NIKE in a stylised word or with a swoosh and a logo only no words ie the Swoosh.
The law of trade marks can be found here http://www.legislation.gov.uk/ukpga/1994/26 (TMA). In short any sign which can be represented graphically and which is capable of distinguishing the goods or services of one undertaking from those of another is prima facie registrable as a trade mark, subject to the “absolute” and “relative” grounds for refusal. This means – you must have a clear and distinctive word logo which sets you apart from other traders offering similar goods and services.
In fashion the selection and purchase of an item of clothing is likely to be based primarily on a visual selection, so make sure your clothing brand is disctinctive.
STELLA MCCARTNEY and VIVIENNE WESTWOOD, AND PAUL SMITH have all registered their names as trade marks for “clothing”.
Slogan marks are subject to the same standards as any trade mark examination process so you must be able to distinguish the goods or services of one undertaking from those of another. Slogans that are common descriptive phrases, such as “LOOKING GOOD” for “clothing”, or “IM WITH HIM” are unlikely to be registrable as they will be deemed too vague, bland and not capable of distinguishing one business from another.
To review how trade marks are interpreted in England and Wales a good starting point would be