It might be possible to get a quote at a pharmacy for the medicines you expect to be prescribed before you are issued a prescription, that way you can decide in advance if you can afford it.
I know mine would cost in excess of £250 per month to buy privately, on the NHS is 3 x £8.40 per month.
I've had quotes for private psychiatrist ranging from £280-£350 per hour.
It's a big financial commitment.

Can I ask why you wouldn't want your NHS GP involved. Do your employer ask for your medical records and does it effect your job?