No, it doesn't work like that in the NHS. I assume you're a doctor in the NHS as you've mentioned the BMA but if not then ignore this.
In the NHS pension scheme, there is no pension pot. Your contributions just go into a general fund that pays existing pensions and yours in time. Your pension value for the purposes of LTA calculation is worked out by taking your estimated annual pension and multiplying it by 23 (lump sum plus 20 years of pension).
Doctors such as consultants and GPs who are old enough to be entirely or mostly on the 1995 scheme are quite likely to breach the LTA, which is currently £1m.
You can still pay into the pension scheme (and get all the tax relief) but when you crystallise your pension and it exceeds the LTA, you will be taxed quite heavily on the excess. However,
If your total pension exceeded £1m (this includes any private pension) as on 31/3/16 then you can apply for individual protection which means that any pension value between £1m and £1.25m will not be subject to the extra tax.
It is certainly possible to stop paying into the scheme when you reach your LTA. Your pension will be index linked until you do retire but you lose your death in service benefits. Another option is to take flexible retirement, collect your pension and negotiate a new contract with your employer on reduced hours. Or retire completely, of course.
You really do need to speak to an independent financial adviser who has knowledge of the NHS scheme. If you don't want to speak to the BMA then maybe you have colleagues who can recommend someone.
I don't know your individual circumstances but feel free to PM me if you wish as I have been through similar issues myself.