Right now the timeframe is 18 weeks but the reality is up to 68 weeks for the first appointment. Most of the work in fixing this needs to come from within the NHS but every individual can do something to help.
In the UK we have the right to request transfer to a different clinic, contact any GIC you can reasonably travel to and ask what their waiting time is, when you find one that can see you in a decent amount of time then ask your gp to refer you.
If the cost of travel puts you off then you may be able to get money refunded.
Charing Cross GIC is swamped, it seems that every gp automatically refers patients there as if they don't know other clinics exist, if we can spread ourselves around other clinics then we can ease the pressure on CHX GIC.
I will repeat that most of the emphasis is on the NHS to solve this issue but we can help ourselves a bit