When it comes to structural beams and signs of movement, you will need to employ the services of a structural engineer Structural Engineer | TrustATrader
Though it is possible to do the work yourself and save a lot of money, you are best of going through Building Control for this sort of work. Building regulations approval: When you need approval - GOV.UK (www.gov.uk)
The Structural Engineer will work out the calculations needed for the new beam, this is then sent to Building Control and they will oversee that the work is done correctly.
You can use private Building Control contractors instead of going through your local council
Private Building Control Vs Local Authority Building Control (extensionarchitecture.co.uk)
