Can an employer change any policies and procedures within the organisation, without consulting with staff, as long as it is communicated to them afterwards?

This will depend on whether the policies / procedures in question, or the relevant provisions contained therein, are contractual. 

Contractual terms can normally only be amended with the employee’s consent. In other words, an employer cannot make a “unilateral” change to such terms. Policies will often contain clauses expressing that the policy is non-contractual. In doing so, an employer has much more scope to modify non-contractual provisions or arrangements at any time without securing the agreement of staff.

Many policies and procedures which an employer puts in place do not necessarily form part of the contract of employment, but instead are to be regarded as "works rules" which