Yes. A letter of intent (sometimes called heads of terms or a memorandum of understanding) is typically signed by the parties. It is usually not legally binding, save in respect of certain matters such as obligations relating to exclusivity, confidentiality, governing law, costs, etc.

• Exclusivity: It is customary to include binding exclusivity provisions in a letter of intent or term sheet.
• Break fee: Break fees are not commonly included in private M&A transactions.
• Confidentiality: It is customary to include binding confidentiality provisions in a letter of intent or term sheet.

Confidentiality agreements and exclusivity agreements are often negotiated as separate agreements in private M&A transactions.

English contract law does not impose a general duty to negotiate in good faith. Subject to any agreement between the parties to the contrary (perhaps in a letter of intent), generally there is no recourse or liability to pay damages if an acquisition agreement is not signed. On the other hand, failure to complete an acquisition agreement that has been signed will usually result in liability for the party in default to pay wasted costs, etc. and depending on the provisions of the acquisition agreement, perhaps also damages for loss of bargain.