Here is my timeline if anyone finds this useful. This takes place in Canada, but I find the process the same between Canada and the UK. They most likely will keep you updated about your application process. If you are not selected for a role, they’ll inform you, and vice versa if you are selected for an interview.
I applied for an Engineering position at Mott MacDonald for the Toronto office on Nov 6, 2023. Took the interview on Dec 4. On Dec 8, they sent me a code form to fill out. Now is the waiting.
So if you’ve taken an interview, look out for a code form that they will prob send after the interview. Good luck!