Arrghhhh . . . . . . Not read all of the post. I just saw the subject and realized that it would be a minefield, just like pensions themselves.
So ask some questions and try to understand the answers. Burying your head in the sand could leave you at the mercy of the state, living on benefits in old age.
Even with money in sitting pension funds I can't figure out the best thing to do. Seem to get screwed regardless, tax, fees whatever.
There is no tax on monies you pay into a pension pot - in-fact the govt boosts it up by 25%. There is no tax on the assets/funds contained in the pension pot as it (hopefully) grows. Then when you come to draw it out again (at age 55 or older), 25% of your pot can be taken tax free, and the remainder taken as income, taxed at whatever your tax rate is. You have a personal tax free allowance - currently £11850 - so you can draw out £11850 tax free between age 55 and 67. At 67 your state pension will start giving you an additional £8K+ income. This means you can continue to draw an additional £3K ish from the private pension making a total of £11850 still - and still all tax free.
If you want to take more than £11850 total per annum, then you're going to be paying income tax (at 20%) on everything above the £11850.
There will be fees though - the pension companies have to be paid somehow. You do want to keep these as small as possible. It's possible to get fees down to less than 0.3% per year, though it does depend on what you invest in. You shouldn't be paying more than about 1% though unless you're investing in something very specialised.
Whatever size of 'pot' you build, it should be possible to take an income of somewhere between 3%-4% per annum from it without you risking it running out before you die. Therefore if you want to draw £20K per year in retirement (including £8K state pension), then you need to build a pot of around £400K-£500K. The sooner you start the sooner you'll get there. If you never start, then sooner or later you'll have to get used to living on the £8K state pension alone.