To be patentable your invention must be at least new. That means you cannot tell anyone about it without any prior agreement to maintain secrecy. Your local patent attorney will be able to advise you as to what you can do thereafter. If you don't know how to find one contact the Chartered Institute of Patent Attorneys at www.cipa.org.uk and they will help you.
Bottom line? Don't tell a soul before going to a patent attorney. Most will give you 30min advice for free but charges will accrue for detailed advice and filing. Don't bother going to a solicitor since it needs someone who does it every day, like me actually...Good Luck!