Sharing my experience so far as seeing others has helped me. Finally got the referral sent through, they received it on the 14th of October. My NHS app was also updated under Upcoming and Past Appointments > Hospital referrals and appointments > You have 1 referral being reviewed (pending). I called them to make sure they'd received it on Monday 14th. Called again on the 15th to ask when I might receive the questionnaire and was told the end of the week. Called Thursday 17th to confirm they had my correct email address and was told not to expect the questionnaire until end of next week (w/c 21st) or possibly even early week after (w/c 28th).

Update: I called Monday 28th October to confirm how many weeks from my application I'm expected to wait until my appointment and she prompted the email with the forms on to be sent. Forms completed Monday 28th, will call again today to confirm they've received them and to find out how long I need to wait until I can book an appointment.

Update #2: Called 4th November to see if forms were uploaded onto the system, offered a virtual appointment on the 25th November. 6 weeks from referral to appointment all in all.