There is, however, a rule that you may not use the R or the RTM symbol next to an unregistered trade mark this is because section 95 of the Trade Marks Act 1994 says this:
(1) It is an offence for a person-
(a) falsely to represent that a mark is a registered trade mark, or
(b) to make a false representation as to the goods or services for which a trade mark is registered knowing or having reason to believe that the representation is false.
(2) For the purposes of this section, the use in the United Kingdom in relation to a trade mark-
(a) of the word “registered”, or
(b) of any other word or symbol importing a reference (express or implied) to registration, shall be deemed to be a representation as to registration under this Act unless it is shown that the reference is to registration elsewhere than in the United Kingdom and that the trade mark is in fact so registered for the goods or services in question.
If found guilty of an offence contrary to section 95 then the person will be liable to a fine not exceeding level 3 on the standard scale.
Â So dont do it!