It is very unlikely that there will be no state pension when you come to retire. For a start any party with this point of view would not be in power for very long, certainly not with a large number of the electorate either being retired or approaching retirement.
With regards to your pension of 40K this sound a large amount if it is per annum, however if this is only a fund value that will provide your pension for you whole retirement, then it is a small amount and I would suspect it would only provide you with an annual pension of about �2500. (This is based upon todays prices)
The issue of contracting out is too hard to explain here, however I can say that it only relates to the Second State Pension and it will have no effect upon your Basic State Pension.
If your company will contribute towards your stakeholder then i would recomend joining. Any help that can be recieved towards providing a retirement fund must be taken.